HADITH BOOKS

Three distinguished scholars categorized these 400 usul in four books which are the main sources of hadith in the Shi'a school of thought: a l-Kafi by al-Kulayni (d. 329 h. ), Man La Yahduruh al-Faqih by al-Suduq (d. 381 h. ), and al-Tahdib and al-Istibsar by al-Tusi (d. 460 h. ). Those three scholars were known as the "three Muhammads" since their first names were all "Muhammad." While those three books are the main sources of hadith for the Shi'a, their authors still did not label their books " sahih. " Although they did their best to gather only authentic traditions, if a particular tradition contradicts the Holy Qur'an then it cannot be accepted as legal and valid. Hadith , according to the Ja'fari school of thought, are accepted only if the Holy Qur'an verifies them, since the Holy Qur'an is the only certain source of guidance.