The Contents of the Books
Unfortunately, the content of the books is not completely known to us. We do not know if they only included jurisprudential issues and commandments or other religion-related issues such as ethics and mental teachings, or they contained all sciences. We do not know if all jurisprudential trivial points were recorded in detail in those books or they only contained principles of jurisprudence, from which the infallible Imams (`a) deducted the minor points. Some traditions imply that all required issues of the Muslims existed in the books.
Muhammad Ibn Muslim says, “I asked Imam Sadiq (`a), ‘Does your scientific heritage of the Prophet (s) include main principles or the exegesis of all the topics people need, such as divorce and legacy as well?’ Imam Sadiq (`a) replied, ‘Imam Ali (`a) has written all scientific issues, even divorce and legacy in that book. If our Imamate be accepted, we have a tradition in every field, which will be executed.’”
Traditions similar to above-mentioned ones reveal that everything, even the compensation (‘arsh) for a scrape on body skin is recorded in those books.
Nevertheless, it is improbable that the mentioned books also include all minor issues in all jurisprudential topics. Everyone familiar with extensive Islamic jurisprudence confirms that including all related issues in a single book –even if it is seventy dhara’– is impossible, especially if it contains other religion-related sciences too. In sum, the exact content of the books is not known.
 Jami’ Ahadith Al-Shi’ah, Vol 1, P. 192.