 The Kharijites considered the caliphate of Abu Bakr and Umar to be rightly guided but believed that Uthman ibn Affan had deviated from the path of justice and truth in the last days of his caliphate, and hence was liable to be killed or displaced.They also believed that Ali ibn Abi Talib committed a grave sin when he agreed on the arbitration with Muʿāwiyah.In the Battle of Siffin, Ali acceded to Muawiyah's suggestion to stop the fighting and resort to negotiation.