The four main Shia books of Hadeeth are Al-Kafi, Al-Faqeeh, Al-Istibsar and Al-Tahtheeb. All of them are published separately and there is a new edition having all these four books in one set of volumes. Most of the narrations in these books are authentic and the number of Hadeeths in these books is much more than the number of the narrations in all the six Sunni books of Hadeeth ( Bukhari, Muslim, Tirmithi, Ibn Maajah, Abi Dawood, and Nasaa'ee.).

Every Shia scholar studies every Hadeeth and researches the chain of narrators and the meanings of the text as he understands and comes out with his own result about the authenticity and the meaning of it. No one can force his opinion on other scholars as scientific research is free in Shia Islam for every qualified scholar. That is why, we do not believe in closing the gate of Ijtihad and research in every narration.

Wassalam.