Muhammad ibn Ya'qub al-Kulayni

Muhammad ibn Ya'qub al-Kulayni (died 329 AH / 941 CE) was a Persian Shia scholar best known for compiling al-Kafi ("the Sufficient"), a vast collection of hadith — reports of the words and deeds of the Prophet Muhammad and, for Shia Muslims, of the Imams from his family. Among Twelver Shia, al-Kafi is counted as the earliest and most esteemed of the "Four Books," the foundational hadith corpus of the school.

He took his name from Kulayn, a village near Rayy (in present-day Iran), where he was born; the year is not recorded in the sources, and modern estimates around 255 AH / 868 CE are conjectural. He studied in Rayy, gathered traditions in Qom — then a major Shia learning center — and eventually settled in Baghdad, where he taught for roughly two decades. He earned the honorific Thiqat al-Islam ("the Trust of Islam"), a mark of the confidence later scholars placed in his reliability as a transmitter.

His lifetime fell within what Twelver Shia call the Minor Occultation (ghayba sughra, 260–329 AH), the period when, in Twelver belief, the hidden twelfth Imam communicated with his community through four successive deputies; that era is traditionally held to have ended the very year al-Kulayni died. He is reported to have completed al-Kafi shortly before his death. He died in Baghdad and was buried there, near the Kufa Gate (Bab al-Kufa).