I am warning you that you will be killed on the bend of this canal and on the level of this low area while you will have no clear excuse before Allah nor any open authority with you. You have come out of your houses and then divine decree entangled you. I had advised you against this arbitration but you rejected my advice like adversaries and opponents till I turned my ideas in the direction of your wishes. You are a group whose heads are devoid of wit and intelligence. May you have no father! (Allah's woe be to you!) I have not put you in any calamity nor wished you harm.
(1). The cause of the battle of Nahrawan was that when after Arbitration Amir al-mu'minin was returning to Kufah, the people who were foremost in pleading acceptance of Arbitration began to say that appointment of anyone other than Allah as arbitrator is heresy, and that, Allah forbid, by accepting the Arbitration Amir al-mu'minin turned heretic. Consequently, by distorting the meaning of "There is no authority same with Allah" they made simple Muslims share their views and separating from Amir al-mu'minin encamped at Hanira' near Kufah. When Amir al-mu'minin learned of these plottings he sent Sa`sa`ah ibn Suhan al-`Abdi and Ziyad ibn an-Nadr al-Harithi in the company of Ibn `Abbas towards them and afterwards himself went to the place of their stay and dispersed them after discussion.
When these people reached Kufah they began to spread the news that Amir al-mu'minin had broken the agreement of Arbitration and that he is again ready to fight against the Syrians. When Amir al-mu'minin learned this he contradicted it whereupon these people stood up in rebellion and encamped twelve miles from Baghdad in the low area of the canal called Nahrawan.
On the other side, after hearing the verdict of Arbitration Amir al-mu'minin rose for fighting the army of Syria and wrote to the Kharijites that the verdict passed by the two arbitrators in pursuance of their heart's wishes instead of the Qur'an and sunnah was not acceptable to him, that he had therefore decided to fight with them and they should support him for crushing the enemy. But the Kharijites gave him this reply, "When you had agreed to Arbitration in our view you had turned heretic. Now if you admit your heresy and offer repentance we will think over this matter and decide what we should do." Amir al-mu'minin understood from their reply that their disobedience and misguidance had become very serious. To entertain any kind of hope from them now was futile. Consequently, ignoring them he encamped in the valley of an-Nukhaylah with a view to marching towards Syria. When the army had been arrayed he came to know that the men desired to deal with the people of Nahrawan first, and to move towards Syria afterwards. Amir al-mu'minin, however, said that they should be left as they were, that they themselves should first move towards Syria while the people of Nahrawan could be dealt with afterwards. People said that they were prepared to obey every order of his with all their might whether he moved this way or that way. The army had not moved when news about the rebellion of Kharijites began to reach, and it was learnt that they had butchered the governor of Nahrawan namely `Abdullah ibn Khabbab ibn al-Aratt and his slave maid with the child in her womb, and have killed three women of Banu Tayyi and Umm Sinan as-Saydawiyyah. Amir al-mu'minin sent al-Harith ibn Murrah al-`Abdi for investigation but he too was killed by them. When their rebellion reached this stage it was necessary to deal with them. Consequently, the army turned towards Nahrawan. On reaching there Amir al-mu'minin sent them word that those who had killed `Abdullah ibn Khabbab ibn al-Aratt and innocent women should be handed over to him for avenging blood. Those people replied that they had killed these persons jointly and that they considered it lawful to shed the blood of all the people on his side. Even at this Amir al-mu'minin did not take the initiative for the battle, but sent Abu Ayyub al-Ansari with a message of peace. So he spoke to them aloud, "Whoever comes under this banner or separates from that party and goes to Kufah or al-Mada'in would get amnesty and he would not be questioned. As a result of this Farwah ibn Nawfal al-Ashja'i said that he did not know why they were at war with Amir al-mu'minin. Saying this he separated along with five hundred men. Similarly group after group began to separate and some of them joined Amir al-mu'minin. Those who remained numbered four thousand, and according to at-Tabari's account they numbered two thousand eight hundred. These people were not in any way prepared to listen to the voice of truth, and were ready to kill or be killed. Amir al-mu'minin had stopped his men to take the initiative but the Kharijites put arrows in their bows and broke and threw away the sheathes of their swords. Even at this juncture Amir al-mu'minin warned them of the dire consequences of war and this sermon is about that warning and admonition. But they were so brimming with enthusiasm that they leapt on Amir al-mu'minin's force all of a sudden. This onslaught was so severe that the foot men lost ground but they soon fixed themselves firmly that the attack of arrows and spears could not dislodge them from their position and they soon so cleared away the Kharijites that except for nine persons who fled away to save their lives not a single person was left alive. From Amir al-mu'minin's army only eight persons fell as martyrs. The battle took place on the 9th Safar, 38 A.H.