After the Battle of Siffin the Kharijites had separated from the community and camped at Harura a few miles from Kufa. Their stand was that Ali had made a mistake in accepting the arbitration of men Ali was asked by them to lead them to war against Muawiyah. Ali had tried to conciliate them, and assured of them that he would lead them to war in case the decision of the umpires was against the injunctions of Islam. Some sort of conciliation was brought about between Ali and the Kharijites, and most of the Kharijites returned to Kufa. The Kharijites were a restive and over sensitive people of the extremist type. The Kharijites slipped from Kufa one by one, established a settlement at Nahrawan, a few miles to the east of the Tigris near Madain. The Kharijites from Basra and elsewhere in Iraq also migrated to Nahrawan Here the Kharijites gathered in strength. They elected an Amir of their own. They were very meticulous in observing prayers and following other injunctions of Islam. They aspired to live sinless lives. They declared that they were not interested in the affairs of this world, and that they had sold their lives to win paradise in the next world. Where a Kharijite picked up a date under a date tree and ate it he subsequently cut his right hand himself on the ground that the eating of the date without purchasing it from the owner amounted to a theft. On the other hand when any Muslim indulged in any controversy with them, they invariably killed him. They held that no one except themselves was a Muslim, and it devolved on them to get rid of such people who did not agree with them. They let loose a reign of terror in the countryside and created a problem of law and order for the administration. When the Kharijites of Basra migrated to Nahrawan they met in the way some Muslims including Abdullah the son of an eminent companion Khabab. The Kharijites killed him as well as the woman who accompanied him.
When Ali was ready for a march to Syria he sent a message to the Kharijites asking them to join him in the march to Syria. Ali brought home to them the point that he had undertaken to lead them to war against Muawiyah after the decision of the arbitrators was known and now that he had repudiated the decision of the umpires and was leading a force to Syria they should 30in his ranks as originally agreed upon. The Kharijites gave an insolent reply to the invitation. They said that when they had asked Ali to lead them to war he was the Caliph of the Muslims, and it was incumbent on them to support him for thereby they were to serve the cause of God. After the decision of the umpires the position had been changed. According to this decision Ali had been deposed, and power had been vested in his rival Muawiyah. In these circumstances Ali was undertaking a campaign against Muawiyah for a personal end. They observed that as the warriors of God, they were committed to fight in the cause of God alone, and not in the cause of any particular person to secure a worldly end.
Ali felt that it was futile to argue with a fanatic people like the Kharijites. He was accordingly of the view that they should march to Syria without bothering for the assistance of the Kharijites. His army men however expressed the view that when they were to be away there was the danger that the fanatic Kharijites would terrorize and murder their families. Ali was accordingly prevailed upon to deal with the menace of the Kharijites before proceeding to Syria. Ali agreed to this view and the force that was to proceed to Syria proceeded to Nahrawan instead.