Ja'far al-Sadiq

Ja'far al-Sadiq ("the Truthful," a title given by later tradition) was a scholar of Medina who became one of the most influential teachers of early Islam. Most sources place his birth around 702 CE (83 AH), though some give c. 700; he died in Medina in 765 CE (148 AH). He was a descendant of the Prophet Muhammad through Ali and Fatima, and son of Muhammad al-Baqir.

In Shia belief he is the sixth imam (divinely guided leader of the community) — a doctrine held by Shia Muslims, not by Sunnis, who revere him instead as a respected transmitter of hadith (reports of the Prophet's words and deeds). Sources describe him keeping clear of the political revolts of his day, including his uncle Zayd's uprising and the Abbasid revolution. Tradition credits a large teaching circle around him; the Sunni jurists Abu Hanifa and Malik ibn Anas are reported to have learned from him, and Twelver Shiism names its school of law "Ja'fari" after him.

After his death his following split: the larger group followed his son Musa al-Kazim and became the Twelvers, while others held that his son Isma'il (who died before his father) or Isma'il's line carried the imamate, becoming the Ismailis. Shia sources report that he was poisoned at the Abbasid caliph al-Mansur's instigation; this is a traditional account rather than an independently established fact.