The Battle of Siffin led to the birth of the first sect among the Muslims which came to be known as the Kharjites. The term literally means separatists, seceder or outgoers. The term is based on a verse of the Holy Quran (4:101) which refers to those who leave their homes among the unbelievers. They also called themselves as the Shurat, i. e. those who sell their lives and property in return for paradise. The movement had its origin among the tribes of Banu Tamim, Banu Bakr, and Banu Hamdan. These people had participated in the revolt against Othman, and were involved in his murder. When Muawiyah raised the cry for vengeance for the blood of Othman, they allied themselves with Ali. They fought on his side in the Battle of the Camel. When Ali led his forces to Syria, these people formed an important component of the army of Ali.
As the Battle of Siffin dragged on without leading to any tangible results these people got wearied of the war. They felt that the war was in reality a struggle for power between Ali and Muawiyah. These people could boast of deep-rooted traditions of democracy, and a struggle for power was repugnant to their way of life. They accordingly came to maintain that it was not advisable for them to be a pawn in the game of king malting. When the troops of Muawiyah displayed the leaves of the Holy Quran on their lances and appealed for decision to the Holy Quran instead of arms, these people responded to the call, and forced Ali to suspend hostilities, although victory for his forces was well in sight.
Thus these people though allied with Ali directly promoted the cause of Muawiyah although he was after their blood because of their involvement in the murder of Othman. Muawiyah was shrewd enough to appreciate their gesture, and in the arbitration agreement that was subsequently drawn up there was no reference to the murder of Othman. The point of dispute to be referred for arbitration was, as to out of Ali and Muawiyah, to whom the sovereignty was to belong. On the return march, these people had second thoughts on the matter. They felt that they had committed a sin in accepting the cease fire. They became critical of the appointment of umpires. They were emphatically of the view that the view that the decision of God alone should be sought for, and it was a sin to vest the decision in the matter in human beings. They blamed Ali for his acceptance of the proposal for the appointment of umpires.
In order to support their stand, they worked out religious dogmas of their fundamental principle was 'La Hukma illa lillah" - no decision except the decision of God. They maintained that they stood for the establishment of the kingdom of God and not of men on the earth. As God was not to rule in person, some Amir had to be appointed, but such Amir was bound to follow strictly the commands of God as revealed in the Holy Quran. The Amir could hold office as long as he observed the commands of God. When there was any dereliction on his part, he was liable to be killed. They acknowledged that they were involved in the assassination of Othman, but they justified this act on the ground that Othman had acted against the commands of God. They held that when any person committed a sin he became a Kafir, and it was necessary for him to offer repentance for re-entry in the fold of Islam. They had committed a sin in accepting the cease fire. They repented publicly and sought the forgiveness of God. They held that they alone wore true believers, and all other persons who called themselves Muslims, but did not subscribe to their views were unbelievers. They maintained that they had the right to kill unbelievers. It followed that they could not live in the midst of unbelievers. On return from Siffin they did not come back to Kufa. Instead they encamped at Harura, a few miles outside Kufa. In this way these people separated from the main body of the Muslims, and came to be known as the Kharjites. Their strength was about twelve thousand. Their leaders were Shabath b Ribi al Riahi; Abdullah b Kauwa al Yeshkuri; Yazid b Qais Al Harabi; and Abdullah b Wahab al Rasibi.