Al-Kafi: Shiite Masterpiece hadith book by Thiqat al-islam Muhammad ibn Ya'qub Kulayni (d. 329/940).
Useful information: The book of Kulayni known as Kafi is divided into three parts: Principles, Branches, and Miscellaneous Articles, and contains 16,199 hadiths. It is the most trustworthy and celebrated work of hadith known in the Shi'ite world.