The practice of the compilers of the usul (may Allah have...

The practice of the compilers of the usul (may Allah have mercy on them) was to give importance to the recording and writing of what they heard from the A’immah of the (‘a).” In his book ash-Shamsayn , Shaykh al-Baha’i says: “It has reached us from our masters ( mashayikh ) -may Allah have mercy upon them– that it was the practice of the compilers of the usul that whenever they heard a hadith from one of the A’immah (‘a), they would immediately record it in their usul so that they might not forget part or all of it in the long run.” It was due to this fact that these treatises ( al-usul ) were relied upon by the scholars, such that if they related a tradition from them they would consider it as correct and reliable.

After mentioning the Four Hundred Treatises in chapter twenty nine of his book ar-rawashih , Muhaqqiq ad-damad asserts, “Let it be known that narrating {a tradition} from the authentic and reliable {Four Hundred} usul is one of the fundamental criteria ( arkan ) for the authentication of a tradition ( riwayah ).” In fact, a great number of the companions of the A’immah (‘a) had undertaken the responsibility of writing the usul such that it is not possible to give a detailed account neither of their names nor their treatises.

Shaykh at-Tusi (may Allah have mercy on them) says in this regard in the beginning of al-Fihrist , “And I do not guarantee to give a complete anthology; for the writings of our associates ( ashab ) and their treatises ( usul ) are almost unrecordable due to their being scattered in different cities.” However, their number is certainly not less than four hundred, as it has been stated by Muhaqqiq Agha Buzurg at-Tahrani in his work adh-dhari’ah .[^1] In his previously mentioned work, Muhaqqiq ad-Damad says: “It is common that the Four Hundred Treatises have been written down by four hundred writers from the disciples of Abu ‘Abdillah as-Sadiq (‘a).

Moreover, there were around four thousand people attending his sittings and relating from him.