As per the source

Imam Ja'far al-Sadiq

Al-Sadiq (the truthful)

Birth: 17 Rabi al-Awwal, 83 AH (Medina)
Martyrdom: 25 Shawwal, 148 AH (Medina; by poisoning, per Shia narration)
Kunya: Abu Abdillah
Relation: Son of Imam Muhammad al-Baqir; the sixth Imam

Biography

Taking advantage of the political vacuum between the fall of the Umayyads and the rise of the Abbasids, he built the broadest school of jurisprudence and hadith transmission in Shia history, training thousands of narrators - the Ja'fari school of law is named after him.

Teachings

Systematic, wide-scale codification of Shia jurisprudence and hadith.

Related occasions

Shahadat of Imam al-Sadiq