Why was Ali ibn Abi Talib assassinated?

Answer 1

Ali ibn Abi Talib was assassinated by a Kharijite Extremist who believed that by attempting to make a peace treaty with Mu'awiya of the Bani Omeya, Ali had demonstrated that he was no longer pure enough to lead an Islamic polity.

Answer 2

Ali ibn Abi Talib was assassinated in 661 AD due to internal conflicts within the Islamic Caliphate. He was targeted by a group of dissidents who opposed his leadership and wanted to take control of the caliphate. The assassination occurred during morning prayers, and Ali sustained a fatal wound which led to his death two days later.