Martyrdom of Imam Jafar

Jafar ibn Muḥammad al-Ṣādiq (Arabic: جعفر بن محمد الصادق‎‎; 702–765 C.E.), commonly known as Ja'far al-Sadiq or simply al-Sadiq (The Truthful), is the sixth Shia Imam. He was a descendant of Ali from his father Muhammad al-Baqir's side and a descendant of Abu Bakr from his mother Farwa's side. He is the last individual to be recognized by all Shia sects as an Imam (except the Zaydiyyah), and is revered by Sunni Muslims as a transmitter of Hadith and a prominent jurist.

Al-Sadiq was born in 702 CE. He inherited the position of imam from his father in his mid-thirties. As imam, al-Sadiq stayed out of the political conflicts that embroiled the region, evading the many requests for support that he received from rebels. He was the victim of some harassment by the Abbasid caliphs, and was eventually, according to most Shi'a Muslims, poisoned at the orders of the Caliph al-Mansur.

He was a significant figure in the formulation of Shia doctrine. The traditions recorded from al-Sadiq are said to be more numerous than all hadiths recorded from all other Shiite imams combined. As the founder of "Ja'fari jurisprudence", al-Sadiq also elaborated the doctrine of Nass (divinely inspired designation of each imam by the previous imam), and Ismah (the infallibility of the imams), as well as that of Taqiyyah. The question of succession after al-Sadiq's death was the cause of division among Shiites who considered his eldest son, Isma'il (who had died before his father) to be the next imam, and those who believed his third son Musa al-Kadhim was the imam. The first group became known as the Ismailis and the second, larger, group was named Ja'fari or the Twelvers.

Al-Sadiq religious views are recorded as authority in the writing of number of contradictory positions. The use of his name as an authority within the Sufi, scientific, Sunni legal, Ismaili and extremist writings shows his importance as a figure within the development of early Muslim thought. According to Ya'qubi it was customary for anyone who wanted to relate a tradition from him to say "the Learned One informed us". Malik ibn Anas, when quoting anything from al-Sadiq, would say "The Thiqa (truthful) Ja'far b. Muhammad himself told me that…" the same is reported from Abu Hanifa. The works attributed to him may be of dubious authenticity, but they do establish his name at least as indicating a mastery of learning generally, and the Islamic sciences in particular.

Though most groups wished to recruit al-Sadiq's legacy for their own cause, the most extensive source for his teachings is to be found within the imami Shiite tradition. For Twelver Shiites Ja'far al-Ṣadiq is the sixth imam who established the Shiism as serious intellectual force in the late Umayyad and early Abbasid periods. According to Tabatabai the number of traditions left behind by al-Sadiq and his father were more than all the hadith recorded from Muhammad and all the other Shiite imams combined. Shiite thought starting with Sayyid Haydar Amuli, and leading to Safavid philosophers like Mir Damad, Mulla Sadra and Qazi Sa’id Qumi continuing to the present day is based on Shiite imam's tradition specially al-Sadiq.