Arbitration between Muawiya and Ali 658CE & Formation of the Party of Kharijites 658CE
The two arbitrators met at Adhruh, about ten miles north-west of Maan in Jordan, in February 658 seven months after the ceasefire at Siffin. Since the terms of reference were not very precise, arguments dragged on, sometimes at cross-purposes.
In the end, the arbitrators came to a curious decision. They announced that both Muawiya رضي الله عنه and Ali رضي الله عنه should step down and a new Caliph be elected. Ali and his supporters were stunned by this decision, which had lowered the Caliph in status to the same level as the rebellious Muawiya, whereas they were expecting the outcome to be merely a formal recognition of Ali's رضي الله عنه Caliphate. Ali was thus outmanoeuvred once again by Muawiyaرضي الله عنه and his friend Amrرضي الله عنه . Ali رضي الله عنه refused to accept the verdict on the grounds that it was not in accordance with the Qur`aan, and hence found himself technically in breach of his pledge to abide by the arbitration. This put Ali رضي الله عنه in a very weak position even among his own supporters, whereas Muawiya, on the other hand, started accepting the allegiance of his troops in Damascus. Ironically, the most vociferous opponents in Ali’s camp were the very same people who had forced him into a ceasefire from the point of victory in the first place and then insisted on the choice of a neutral man like Abu Musa al-Ashariرضي الله عنه to represent them in the arbitration. The battle and arbitration farce settled nothing but instead increased bitterness between the two groups to such an extent that they resorted to cursing each other by name regularly in public prayers. Islam and the empire were both split.
Although, in the excitement of the moment, the slogan 'Let God decide' had the immediate desired religious appeal to most of the people in the battle-field and stopped the fighting, it was so vague as to allow interpretation in different ways. It was only after the truce that the people started thinking of the full implications of what had been agreed. Even before the arbitrators met, Muawiya رضي الله عنه , by this device, had won a tacit victory in this dispute by indirectly getting himself recognised as a party equal in rank to the ruling Caliph, although he was, in fact, his subordinate and a rebel. The two central issues in the dispute were Ali'sرضي الله عنه Caliphate and the punishment for Uthman'sرضي الله عنه murderers.
In the arbitration, Ali’s رضي الله عنه supporters expected only the question of the Caliphate to be discussed without any reference to the regicide, but quite the opposite happened. When the deliberations were announced, Ali رضي الله عنه was clearly and openly the loser, because Muawiyaرضي الله عنه had no Caliphate to be deposed from.
A group of puritan zealots among Ali’s رضي الله عنه supporters were incensed with what had happened and felt that the whole concept of the Caliphate had been discredited by Ali’s رضي الله عنهaction. They revolted against him forming a separate party, known as the Kharijites (meaning 'secede') under the slogan 'No decision (arbitration) but that of God'. In the month of July, Ali suppressed them temporarily in a bloody massacre in which nearly 2,000 of them were killed on the banks of the Nahrawan (in Iraq), but they were to reappear many times under various names in the history of Islam.
The Kharijites formed the first sect to break away from the main stream of Islam. Being completely puritanical in outlook and with a strong dislike for political intrigue, they aspired to live in accordance with the literal interpretation of the Word of God. Because they believed that the basis of rule should be righteous character and piety alone, any Muslim irrespective of nationality and social standing could, in their view, become ruler provided he satisfied the condition of piety.
They sought to enforce the 'Kingdom of God', and considered everyone but themselves as doomed to perdition. Moreover, because of its aggressive idealism, it attracted a large following in times of social or religious unrest and thus presented a dangerous threat to the consolidation of state authority at various periods of history till the Abbasid rule [750-1258]. Although a fanatical religious movement, it gradually absorbed other rebel groups, some intolerant of almost any established political authority. This created internal conflict and disorder which eventually contributed to their virtual, though not complete, destruction.