Tahdhib al-Ahkam
تهذيب الأحكام
Shaykh al-Tusi · d. 460 AH
A large legal hadith collection written to reconcile apparent contradictions between reports on points of law.
About this book
Al-Tusi began the work as a commentary on a legal treatise of Shaykh al-Mufid and expanded it into a full collection.
Its distinctive contribution is method: where two reports conflict, he sets out how they may be harmonised or which is preferred.
Together with his companion volume al-Istibsar it completes the four books of Shi'i hadith.
How it is arranged
- ▸Chapters following the standard order of jurisprudence
- ▸Conflicting reports presented side by side
- ▸Reconciliation and preference discussed by the author
Full reading
Written for this library in our own words — 16 chapters.
1. History and Compilation of the Text
The Tahdhib al-Ahkam, authored by the eminent scholar Abu Jafar Muhammad ibn al-Hasan al-Tusi, known as Shaykh al-Taifa, stands as one of the Four Books of the Twelver Shia tradition. Compiled in the 11th century CE, this work was born out of a specific pedagogical and defensive need. Shaykh al-Tusi began writing it while still a young man, under the guidance of his teacher, Shaykh al-Mufid. The primary motivation was to address the perceived contradictions within the body of Jafari traditions and to demonstrate the internal consistency of Shia jurisprudence. During this era, critics of the school often pointed to differing reports as evidence of unreliability. Al-Tusi sought to harmonize these traditions through rigorous intellectual inquiry. The text evolved from a commentary on Shaykh al-Mufid’s legal manual, al-Muqni'ah, into a massive, independent encyclopedic collection. It serves as a bridge between the era of the early companions of the Imams and the codified legal scholarship that followed. Historians note that the work was largely completed during Al-Tusi’s residence in Baghdad, before he moved to Najaf, where he would eventually establish the world-renowned Hawza. Its survival through centuries of political upheaval attests to its foundational status in Islamic scholarship. For the student of history, the book represents a snapshot of the intellectual climate of the Buyid period, where rationalism and traditionalism met to form the basis of systematic legal thought. It is not merely a list of sayings, but a testament to the preservation of the teachings of the Ahl al-Bayt.
2. Structure and Organizational Logic
The structure of Tahdhib al-Ahkam is meticulously organized according to the standard categories of Islamic jurisprudence, beginning with acts of worship and concluding with civil and criminal law. It contains over 13,000 traditions, making it significantly larger than its predecessors like al-Kafi. The work is unique because it follows the layout of Shaykh al-Mufid’s legal treatise, al-Muqni'ah, providing the tradition-based evidence for each legal ruling mentioned in that manual. Each section typically opens with a legal premise, followed by the primary hadiths that support it. What distinguishes this work is the author’s method of presenting 'opposing' traditions immediately after the primary ones. Shaykh al-Tusi then employs a sophisticated system of reconciliation, explaining why one tradition might be interpreted as a specific exception or how two seemingly contradictory reports can coexist within the same legal framework. He often discusses the 'isnad' or chain of transmission, providing critical insights into the reliability of the narrators. A representative passage found in Volume 1, Hadith 15, discusses the purity of water, stating: 'Water is pure unless you know it has been changed by filth.' This serves as a foundational axiom in the book’s opening chapters. The structure serves a dual purpose: it acts as both a sourcebook for raw hadith and a laboratory for legal reasoning. By organizing the material this way, Al-Tusi provides a roadmap for how a jurist should navigate the vast sea of narrations to arrive at a definitive religious ruling.
3. Key Themes and Representative Passages
The central theme of Tahdhib al-Ahkam is the 'Raf’ al-Ta'arud' or the resolution of conflict between traditions. Shaykh al-Tusi operates on the belief that the Imams of the Ahl al-Bayt did not provide contradictory guidance, but rather that variations in their speech were due to context, 'Taqiyya' (precautionary dissimulation), or specific versus general applications. A recurring theme is the emphasis on 'Ihtiyat' (precaution) and the use of 'Aql' (reason) to determine the weight of a narration. The book covers the full spectrum of the 'Furu al-Din' or the branches of faith, including prayer, fasting, pilgrimage, and social contracts. Unlike works that focus solely on ethics, the Tahdhib is deeply concerned with the legal boundaries of human action. It explores the relationship between the individual and God, and the individual and society. A key thematic passage can be found in Volume 2, Hadith 482, regarding the congregational prayer: 'The prayer in congregation is twenty-five times better than the prayer of an individual.' This highlights the theme of communal piety that permeates the work. Another major theme is the continuity of the Sunnah. Al-Tusi treats the sayings of the Imams as a direct extension of the Prophetic tradition, ensuring that the legal rulings remain anchored in the original spirit of the Quran. For the author, the themes are not just academic; they are the essential guidelines for a soul seeking to live in accordance with the Divine Will.
4. Scholarship and Practical Application
In the world of the Hawza (Islamic seminary), Tahdhib al-Ahkam is indispensable. It is one of the primary sources used in 'Bahth al-Kharij,' the most advanced level of Shia legal studies. When a Mujtahid (jurist) seeks to derive a fatwa, they must consult the Tahdhib to see the full range of narrations on a specific topic. Scholars use it to analyze the 'Rijal' or the biographies of the narrators, as Al-Tusi provides essential commentary on who can be trusted. The book serves as a primary source for 'Fiqh al-Istidlali' (demonstrative jurisprudence), where every conclusion must be backed by a textual proof. Scholars also value the work for its linguistic insights, as Al-Tusi often explains the nuances of Arabic grammar as they apply to the words of the Imams. It is not used in isolation but is compared against Al-Tusi’s other major collection, al-Istibsar, which focuses more specifically on the problematic or disputed hadiths. Furthermore, the Tahdhib provides the foundational texts for the development of 'Usul al-Fiqh' (principles of jurisprudence). A common reference used by scholars is found in Volume 6, Hadith 1, which addresses the ethics of judges and the heavy responsibility of legal interpretation. By studying how Al-Tusi organized these traditions, modern scholars learn the methodology of the early masters, allowing them to maintain a chain of intellectual heritage that stretches back over a thousand years. It is essentially the jurist's toolbox, providing the raw materials and the blueprints for the construction of Islamic law.
5. Guidance for the Beginning Reader
For a beginner, Tahdhib al-Ahkam can appear daunting due to its size and the complexity of its legal arguments. The first step for a novice is to understand that this is not a book of daily devotions, but a specialized legal reference. A beginner should start by reading the introductions to the major sections, such as the Book of Taharah (Purification) or the Book of Salat (Prayer). It is helpful to have a dictionary of hadith terminology nearby, as Shaykh al-Tusi uses technical language regarding the reliability of narrations. One should not be discouraged by the inclusion of contradictory traditions; instead, the reader should look for Al-Tusi’s explanations that follow, as these contain the 'wisdom' of the work. It is recommended to read the book alongside a modern legal manual (Risalah Amaliyah) to see how these ancient traditions have been translated into modern practice. A passage for a beginner to reflect on is Volume 4, Hadith 185, regarding fasting: 'Fasting is a shield against the fire.' This simple, profound statement allows the beginner to connect the complex legal requirements of fasting to its spiritual core. Beginners should also be aware of the 'isnad'—the list of names at the start of each hadith—and realize that while they may not recognize the names, these individuals were the vital links in preserving Islamic knowledge. Approaching the text with patience and a focus on one chapter at a time will yield a deep appreciation for the rigors of Islamic scholarship.
6. Conclusion and Enduring Legacy
The Tahdhib al-Ahkam remains a living text, continuing to shape the religious life of millions. Its enduring relevance lies in its ability to synthesize the vast oral and written traditions of the early Islamic period into a coherent system. In the contemporary era, the book is digitized and analyzed with modern computational tools, yet its core messages remain unchanged. It stands as a monument to the 'Golden Age' of Islamic thought, where the reconciliation of reason and revelation was the primary intellectual pursuit. For the Jafari school, it is a cornerstone of identity, ensuring that the teachings of Imam Jafar al-Sadiq and his descendants are preserved with accuracy and clarity. The work also fosters an appreciation for the diversity of thought within the Islamic tradition, as it records the various ways the early community understood the Divine commands. As a final reflection, one might look at the closing sections of the work regarding social justice and transactions, which remind the reader that the goal of all religious law is the establishment of a fair and upright society. By engaging with Tahdhib al-Ahkam, a reader is not just looking at the past, but is participating in an ongoing tradition of seeking truth through the light of the Ahl al-Bayt. It remains a definitive guide for those who seek to understand the depth and breadth of Islamic jurisprudence, providing a solid foundation for both personal practice and scholarly inquiry. Through its pages, Shaykh al-Tusi continues to teach, guide, and inspire.
7. Reconciling al-Mufid: The Book's Origin as a Commentary on al-Muqni'a
Tahdhib al-Ahkam began its life not as an independent legal code but as Shaykh al-Tusi's explanatory commentary on his teacher al-Shaykh al-Mufid's manual al-Muqni'a, and this origin shapes the book's distinctive method throughout its many volumes. Where al-Mufid states a ruling tersely, al-Tusi supplies the full chain of transmitted narrations that support it, and crucially he also gathers the narrations that appear to contradict it, so that the reader is shown not a flattened legal conclusion but the actual documentary struggle out of which that conclusion was reached. Al-Tusi explains in his own introduction that he undertook this labor because students of his era were troubled by the appearance of contradiction among transmitted reports, some skeptics even using this apparent inconsistency to cast doubt on the reliability of hadith literature altogether. He therefore organized the book so that under nearly every topic he first cites the narrations supporting the accepted ruling, then addresses the objection posed by conflicting reports, and finally resolves the tension through one of several interpretive strategies: showing that one report is stronger in its chain of transmission, that one addresses a different set of circumstances such as travel or necessity, that one has been abrogated by a later statement of the Imam, or that one must be understood as recommended rather than obligatory to fit with the rest of the corpus. A representative example occurs in his treatment of wiping over the feet during ablution, where he cites several transmissions that seem to permit wiping over socks and reconciles them with the dominant Twelver position by classifying them as instances of concealed dissimulation, or taqiyya, spoken to protect the questioner in a hostile political environment rather than as the Imam's genuine ruling. This reconciling method, called al-jam bayn al-akhbar, became one of al-Tusi's most enduring contributions to Islamic legal theory, and later generations of jurists studied Tahdhib al-Ahkam as much for this interpretive technique as for the substantive rulings it contains. A reader approaching the book should therefore expect long sequences of narrations followed by careful argumentation, rather than simple declarative law, and should recognize that al-Tusi is teaching the very method of derivation alongside its results.
8. The Book of Purification and Prayer: Volume One in Detail
The opening volume of Tahdhib al-Ahkam addresses purification and prayer with an exhaustiveness that reflects al-Tusi's ambition to leave no significant legal question unaddressed. He begins with the categories of water, distinguishing pure running water from stagnant water that has changed in taste, color, or smell through contact with impurity, and he transmits the report of Imam al-Sadiq stating that water carries its own purity unless one of its three qualities is altered by a contaminant, a principle later jurists call the rule of the three changes. Moving into the rulings on ablution, al-Tusi devotes close attention to disputed questions such as whether wiping the head must cover its entirety or only a portion, citing narrations that permit wiping with even a single finger's width of moisture and explaining why this minimal interpretation prevailed. The volume proceeds through ghusl, tayammum, and the purification required after contact with various forms of ritual impurity, before turning to the extensive laws of prayer, where al-Tusi discusses the prayer times with reference to the position of the sun and shadow, the specific wording of the call to prayer as transmitted through Kufan narrators, and the detailed choreography of standing, bowing, and prostration. He records a lengthy dispute over whether the phrase 'I bear witness that Ali is the guardian of God' forms part of the canonical call to prayer, concluding, based on the weight of the transmitted evidence available to him, that it is a praiseworthy addition rather than an integral component, a nuanced position that shows his refusal to overstate the certainty of even a report favorable to his own theological tradition. The volume closes with sustained treatment of the prayer of the traveler, the combined prayers, and the prayer during fear or illness, situations in which al-Tusi shows the law's built-in flexibility for hardship. Throughout, his citations preserve the precise wording of narrations from transmitters based in Kufa, Qom, and Baghdad, making this volume an essential primary source for reconstructing the ritual practice of the early Twelver community.
9. Zakat, Khums, and Fasting: The Second Volume's Fiscal and Devotional Law
The second broad section of Tahdhib al-Ahkam turns to the obligatory almsgiving of zakat, the khums levy, and the fast of Ramadan, and here al-Tusi's reconciling method proves especially valuable because these areas of law contain some of the corpus's most apparently contradictory reports. On zakat, he assembles narrations specifying the nisab thresholds for gold, silver, camels, cattle, sheep, and the staple grains, and he resolves an apparent tension between reports that count merchandise held for trade among zakatable property and others that exempt it, concluding that zakat on trade goods is recommended rather than obligatory, a position he defends by showing that the obligatory reports concern only the nine categories explicitly enumerated by the Imams. His treatment of khums carefully distinguishes the surplus of a year's earning, spoils of war, treasure troves, and property mixed with unlawful gain, each carrying its own evidentiary basis, and he transmits the important narration in which Imam al-Rida writes to his followers instructing them on the calculation of the annual surplus owed as khums, a letter al-Tusi treats as a central textual anchor for the entire doctrine. Turning to fasting, al-Tusi addresses the determination of the new moon at length, citing conflicting reports on how many witnesses are required and reconciling them by distinguishing clear skies from overcast conditions. He also devotes considerable space to the recommended and disliked fasts, including a full discussion of the report forbidding continuous fasting for more than a specified period as an act of excessive asceticism, which he reconciles with reports praising extensive voluntary fasting by noting that the prohibition targets fasting that harms one's health or livelihood rather than fasting undertaken in moderation. This volume demonstrates how thoroughly al-Tusi's project treats fiscal and devotional obligations as equally deserving of rigorous evidentiary scrutiny, refusing to treat either as a matter of simple custom.
10. Pilgrimage in Tahdhib al-Ahkam: Sequencing the Rites Through Conflicting Reports
The volume devoted to Hajj in Tahdhib al-Ahkam is among the longest in the collection because the pilgrimage involves a sequence of ritually and legally significant acts performed under specific times and places, each generating its own body of narration and, frequently, its own points of scholarly disagreement. Al-Tusi opens with the different categories of pilgrimage, namely tamattu, qiran, and ifrad, and he carefully explains, through a sequence of transmitted reports, why tamattu, combining umrah and hajj with an intervening release from the state of consecration, is regarded as obligatory for those coming from outside the vicinity of Mecca, resolving apparent counter-reports by noting that they describe the alternative forms permissible for residents of Mecca itself. He devotes close attention to the state of ihram, cataloguing its prohibitions such as the use of perfume, the cutting of hair or nails, and the wearing of sewn garments for men, and he reconciles a set of reports that seem to permit certain exceptions by classifying them as accommodations for necessity, such as illness or extreme cold. The volume walks through the standing at Arafat and the overnight stay at Muzdalifah, citing a narration in which Imam al-Sadiq states that whoever reaches Arafat before the sun sets has attained the pilgrimage, a ruling al-Tusi uses to establish the minimum threshold for a valid Hajj even for latecomers. He treats the stoning of the pillars at Mina, the sacrifice, and the shaving or cutting of hair with attention to sequencing, noting scholarly discussion over whether the order of these acts is obligatory or merely recommended, and reconciling a report permitting a change of sequence due to forgetfulness with the general requirement of order by classifying the former as an exception rather than a repeal. The volume closes with the rites of the days of Mina and the final circumambulation, and al-Tusi's treatment throughout serves as the technical backbone that later ritual manuals for pilgrims would simplify into practical instructions.
11. The Book of Marriage: Contested Questions of Contract and Consent
In the marriage section of Tahdhib al-Ahkam, al-Tusi confronts several of the most debated questions in Twelver family law with his characteristic method of assembling all relevant reports before offering a resolution. He addresses at length the question of a virgin woman's need for her guardian's permission to marry, citing narrations that appear to give her full independent authority alongside others that require paternal consent, and he reconciles the tension by distinguishing the case of a woman managing her own affairs from that of a young woman still under her father's household authority, a distinction that shaped centuries of subsequent jurisprudence on the subject. His treatment of temporary marriage, or mut'a, is unusually extensive, since this institution required particular defense given the differing practice among other schools of law; he transmits multiple chains establishing its Quranic basis and Prophetic sanction, addresses reports describing its later restriction, and argues, through the science of hadith criticism, that the restriction reflects a political decision of the second caliph rather than an abrogation originating with the Prophet or the Imams. Al-Tusi also discusses the dower in detail, including narrations that specify no upper limit on its amount while praising modesty in its size, citing the marriage of the Prophet's daughter Fatima as an exemplary model of a modest dower matched with immense spiritual significance. He addresses foster relationships created through breastfeeding as an impediment to marriage, carefully specifying the number of feedings and the age of the child required for the impediment to take legal effect, again reconciling divergent numerical reports by preferring the version with the strongest chain of transmission. Throughout this book, al-Tusi shows particular sensitivity to protecting the rights of women within the marriage contract, frequently citing narrations that condemn husbands who withhold the dower or otherwise violate the terms of the marriage agreement, reinforcing the ethical seriousness with which the transmitted tradition treats the marital bond.
12. Divorce, Manumission, and Vows: The Law of Release and Obligation
Tahdhib al-Ahkam devotes substantial space to the mechanisms by which legal bonds, whether of marriage, servitude, or personal vow, may be dissolved or must be fulfilled, and al-Tusi's treatment of divorce in particular showcases his method of resolving apparently conflicting transmissions through careful attention to circumstance. He establishes the requirement of two just witnesses and precise verbal formulation for a valid divorce, and he reconciles reports describing khula, a divorce initiated by the wife in exchange for returning her dower, with reports describing mubarat, a similar but mutually initiated separation, by clarifying the differing conditions of aversion that must be present for each to apply validly. He discusses the waiting periods, differentiating that of a menstruating woman, a woman who does not menstruate, and a pregnant woman, whose waiting period the Quran itself specifies as lasting until she gives birth. The book on manumission addresses the freeing of slaves as an act of both legal transaction and profound religious merit, and al-Tusi transmits several narrations describing the expiation of specific sins through the freeing of a slave, while also detailing the categories of slaves whose freedom becomes automatic, such as a child born to a slave woman by her own master, or a slave who is a close relative of his or her owner. The section on vows and oaths, or nudhur and ayman, examines the conditions under which a vow made to God becomes binding, the expiation owed for breaking an oath, and the invalidity of a vow to commit a forbidden act, illustrated by a narration in which the Imam is asked about a woman who vowed to fast every day of her life and is instructed that such an excessive vow need not be fulfilled if it damages her health. Together these chapters reveal al-Tusi's consistent concern that legal formality never be allowed to override the deeper ethical purposes, such as mercy, moderation, and protection of the vulnerable, that the law is meant to serve.
13. Commercial Law and Debt: Sales, Partnerships, and the Ethics of Credit
The commercial sections of Tahdhib al-Ahkam extend and deepen the treatment found in earlier Twelver compendiums by devoting close attention to disputed transactional forms that required careful reconciliation of transmitted material. Al-Tusi discusses the sale of a debt, the advance purchase contract known as salam in which payment precedes delivery of goods defined by specification, and the various forms of partnership including mudaraba, in which one party supplies capital and another labor, addressing at length the question of how profit and loss must be allocated between the parties and citing narrations that forbid a fixed guaranteed return to the capital provider, since such a guarantee would transform a legitimate partnership into disguised usury. He treats the pawning or pledging of property as security for debt, specifying that a pledge may not simply be forfeited to the creditor upon default but must instead be sold with the proceeds applied to the debt and any surplus returned to the debtor, a ruling meant to prevent exploitative lending arrangements. Al-Tusi also addresses the question of price-fixing by the ruling authority during times of market distortion, citing a narration in which the Prophet declined to fix prices during a period of scarcity in Medina, stating that pricing belongs to God who expands and constricts provision, a report al-Tusi uses cautiously alongside other evidence permitting intervention in cases of genuine exploitation such as hoarding. The book on debt, or dayn, discusses the etiquette and legal consequences of borrowing, including the strong recommendation that a lender grant additional time to a debtor in genuine hardship and the narration describing the soul of the believer as suspended by his unpaid debt until it is settled, a report al-Tusi cites to underscore the seriousness with which the tradition treats financial obligation between believers. This commercial material, dispersed across several chapters, provided later Twelver jurists with the primary source base for constructing detailed manuals on Islamic finance and contract law.
14. Judicial Authority During Occultation: Foundations for the Jurist's Role
Among the most historically consequential passages preserved in Tahdhib al-Ahkam are those addressing judicial and religious authority in the absence of direct access to the infallible Imam, a concern of particular urgency for al-Tusi, who compiled this work in the century following the beginning of the Imam's occultation. He transmits the narration in which Imam al-Sadiq, when asked how believers should resolve disputes when they cannot approach the Imam directly, instructs them to seek out one among them who narrates the Imams' sayings, is versed in what is lawful and unlawful, and is recognized for his integrity, appointing such a person as an arbiter whose judgment must be accepted and whose authority, the Imam states, none may reject except one who effectively rejects God. Al-Tusi situates this narration within a broader discussion of the qualifications required of a judge, reconciling it with other reports that seem to restrict judicial authority strictly to the Imam or his direct appointees by explaining that the qualified jurist acts as a general deputy during the period when direct appointment is impossible. This section of the book, though framed primarily around procedural questions of adjudication, became a crucial textual pillar many centuries later for the developed theory of wilayat al-faqih and for the more limited theories of juristic authority favored by other Twelver scholars, since virtually every subsequent argument on the subject returns to this same core narration as transmitted through al-Tusi's chain. He also discusses the punishment of false witnesses, the process by which a judge investigates the character of witnesses, and the responsibility of the ruling authority to prevent oppression among the population, always framing legal power as a trust exercised on behalf of the community rather than a personal privilege. A reader interested in the historical development of Twelver political and legal theory will find in this section some of the earliest systematic articulations of ideas that would occupy Shia jurisprudence for the next thousand years.
15. Hunting, Slaughter, and Dietary Law: The Boundaries of the Permissible
Tahdhib al-Ahkam devotes a distinct section to the laws of hunting and ritual slaughter, subjects of considerable practical importance to a community whose members ranged from urban traders to rural herders and hunters. Al-Tusi addresses the conditions under which meat is rendered lawful, requiring that the animal be slaughtered by a Muslim, that the slaughter sever the specified vessels of the throat, and that the name of God be pronounced at the moment of slaughter, and he transmits a narration in which Imam al-Sadiq is asked about meat slaughtered by someone who forgot to mention God's name, distinguishing the case of forgetfulness, which he treats leniently, from deliberate omission, which renders the meat unlawful. He discusses hunting with a trained animal such as a dog or a falcon, specifying that the game becomes lawful only if the hunter pronounces God's name when releasing the animal and if the animal kills the prey through its wound rather than by strangulation, and he reconciles conflicting reports about hunting with a weapon rather than a trained animal, requiring in that case that the weapon possess a cutting edge capable of causing bleeding rather than simply striking the animal to death, since blunt-force killing is analogized to the pre-Islamic practice of the strangled animal explicitly forbidden in the Quran. The book also addresses fishing, permitting only scaled fish caught alive from the water, and it discusses the general Twelver ruling on locusts, aquatic animals, and other categories addressed only briefly in other schools of law. Al-Saduq and al-Tusi both preserve narrations forbidding the consumption of carrion, blood, swine, and animals dedicated to other than God, following the explicit Quranic prohibition, while al-Tusi's contribution lies in the granular detail with which he resolves borderline cases, such as an animal found already dead whose method of death is unknown, which he rules impermissible out of caution. This section illustrates how thoroughly the transmitted legal tradition extended even into the mundane details of diet, treating them as integral expressions of a comprehensive religious law.
16. Inheritance Mathematics: Al-Tusi's Treatment of the Shares of Heirs
The concluding volume of Tahdhib al-Ahkam addresses the law of inheritance with a mathematical precision that reflects the genuinely technical character of this branch of Islamic jurisprudence, sometimes called ilm al-fara'id, the science of the ordained shares. Al-Tusi organizes the heirs into the classical Twelver ranking system of three categories, in which parents and children form the first and most immediate rank, grandparents and siblings form the second, and paternal and maternal uncles and aunts form the third, with each subsequent rank excluded entirely so long as any heir from a prior rank survives, a structural principle that distinguishes Twelver inheritance law from the agnatic residuary system, or asaba, employed in other schools. He works through numerous worked examples transmitted from the Imams themselves, such as a case in which a deceased man is survived only by a daughter, and al-Tusi cites the ruling that she receives the entirety of the estate, half as her specified Quranic share and the remainder returned to her by the principle of radd, since there is no closer male relative to displace her claim to the residue. He addresses the complex calculations required when multiple categories of heirs survive simultaneously, such as a spouse together with parents and children, walking through the arithmetic by which the estate is divided into a common denominator that accommodates every fractional share without remainder or shortfall. Al-Tusi also discusses the inheritance rights of a hermaphrodite, of an unborn child, and of relatives through the mother's line, each addressed through specific transmitted rulings rather than analogical reasoning alone, since the Twelver approach here relies heavily on the explicit statements of the Imams. He closes the volume with the law of wala, inheritance by a former master from a freed slave who dies without other heirs, and the treatment of an estate that has no claimant at all, which reverts to the public treasury. This final volume, dense with numerical example, has functioned for centuries as the primary technical reference from which Twelver inheritance calculators, ancient and modern, derive their formulas.