Al-Kāfī (Arabic: الکافي, the Sufficient) is a collection of hadith of the Twelver Shi'a. It is the most important and authentic collection among the Four Books. It was compiled by thiqat al-Islam al-Kulayni (d. 329/941) in the period of the Minor Occultation. Al-Kafi consists of three parts: Usul (principles), Furu' (branches), and Rawda (miscellaneous issues); Usul is the most important part. Al-Kulayni tried to collect hadiths in such a way that they agree with the consensus and there is no incompatibility between them and the Qur'an.
Author: Abū Jaʿfar, Muḥammad b. Yaʿqūb b. Isḥāq al-Kulaynī Al-Rāzī