Two books by one great scholar: Shaykh al-Tusi — Muhammad ibn al-Hasan al-Tusi (d. 460 AH / 1067 CE), student of Shaykh al-Mufid and Sayyid al-Murtada — wrote two of the four books. When Seljuk mobs burned his house and library in Baghdad, he moved to Najaf and founded the Hawza there, which is still active today.
Tahdhib: the largest and most open: Tahdhib al-Ahkam holds 13,590 narrations in 10 volumes — the largest of the four books. It began as a commentary on al-Mufid's legal manual Al-Muqni'a, giving the Hadith evidence behind every ruling. Al-Tusi does not just list narrations — he explains WHY he includes each one and how apparent contradictions are resolved. That makes Tahdhib the most transparent of the four. About 45% of its narrations are considered Sahih or Hasan.
Istibsar: the book of contradictions: Al-Istibsar holds 5,511 narrations in 10 volumes. It is the only Hadith book ever written to present narrations that appear to contradict each other — and resolve them, step by step. Its four rules are: Tarjih — prefer the stronger narration (about 60% of cases); Jam' — reconcile both narrations (about 25%); Takhsis — the specific narration limits the general one (about 10%); and Naskh — the later teaching supersedes the earlier one (about 5%, used very sparingly).
Four books, one library: Together, the four books hold about 41,000 narrations, compiled between 329 and 460 AH. No single book is enough alone: find the narration in Al-Kafi or Man La Yahduruhu, check the evidence in Tahdhib, and resolve contradictions in Istibsar. Beyond the four, Bihar al-Anwar (Allama Majlisi, 110 volumes) gathers every Shia narration, and Wasa'il al-Shia (Hurr al-Amili, 30 volumes) organises the legal narrations by chapter.
Example
Two Hadith seem to disagree about prayer time: one says prayer at such a time is forbidden; another equally strong one says it is permitted. Al-Istibsar shows they can both be right — the first is about voluntary prayer, the second about obligatory prayer. That is Jam' — reconciliation. Both narrations stay; the contradiction disappears.
Key Terms
- Tahdhib al-Ahkam (تہذیب الاحکام) — al-Tusi's book of legal Hadith; the largest of the four
- Al-Istibsar (الاستبصار) — al-Tusi's book that resolves contradictory narrations
- Tarjih (ترجیح) — preferring the stronger narration when two conflict
- Jam' (جمع) — reconciling two narrations so both can be correct
Quran or Hadith
Imam al-Sadiq (as) said: "When two contradictory narrations reach you — compare both to Allah's Book. Take what agrees with Allah's Book; reject what contradicts it." — Al-Kafi. — to be checked. This is the Quran's role in resolving contradictions, before Tarjih, Jam', or any other rule.
Fresh diagram to be drawn: A four-book shelf: Al-Kafi (16,199), Man La Yahduruhu (5,998), Tahdhib (13,590), Al-Istibsar (5,511), with a banner above: "About 41,000 narrations — one library", and two more books behind them: Bihar al-Anwar (110 vols) and Wasa'il al-Shia (30 vols).
- Shaykh al-Tusi wrote two of the four books: Tahdhib al-Ahkam and Al-Istibsar.
- Tahdhib is the largest book (13,590 narrations) and explains WHY each narration is included.
- Al-Istibsar resolves contradictions with four rules: Tarjih, Jam', Takhsis, and Naskh.
- The four books together hold about 41,000 narrations.