Many of the Kharijis, after the battle of Nahrawan, had gone to Mecca, where they had frequent political meetings in the holy sanctuary, devising plans to avenge their relatives who had fallen in Nahrawan. Here too, they planned the murder of Ali and Muawiya, adding a third name to the list of Amr bin al-A'as. The three Meccan Kharijis, Abdur Rahman bin Muljam al-Sarimi, Burk bin Abdullah, and Amr bin Bakr volunteered to come forward. Abdur Rahman agreed to kill Ali, Burk to Muawiya, and Amr to murder Amr bin al-A'as, now the governor of Egypt. The morning of Friday, the 17th Ramdan was fixed for the execution. The three assassins poisoned their swords and separated. Abdur Rahman took the route of Kufa, Burk that of Damascus and Amr that to Egypt. The chosen day arrived and Burk bin Abdullah, in Damascus, attacked Muawiya while he was in the mosque, and wounded him in the loins. He was arrested. Muawiya ordered his men to cut off the feet of Burk and take out his tongue. He was then dragged to be further tortured and put to a cruel and ignominious death. In Egypt, Amr bin Bakr went to the mosque on the morning of 17th Ramdan to assassinate Amr bin al-A'as. In his stead, his deputy, Kharja bin Huzafa was in the mosque. Amr bin Bakr, who had never seen either of them before, slew Kharja with one stroke of his sword. He was arrested and was forthwith put to a cruel death.
Of the three assassins, it was Abdur Rahman who had the easiest task for Ali. He went to the cathedral mosque of Kufa just before the break of dawn, where he took up his position in the narrow passage leading to the mosque and waited for Ali to enter. The moment Ali set foot in the mosque, while it was still dark, the assassin attacked with the sword, but missed his aim. When Ali was in prostration, Abdur Rahman struck Ali the point of his poisoned sword and fled away. Shortly afterwards the congregation began to assemble in the mosque for the dawn prayers, and there they found Ali lying wounded on his prayer mat. Abdur Rahman was soon arrested, but no antidote could be found for the poison and Ali's condition rapidly deteriorated, and died on 21st Ramdan, 40/January 29, 661 at the age of 63 years, and bequeathed the office of Imamate to his son Hussain.
The period of Ali's caliphate lasted for 4 years and 9 months, and the period of his Imamate since the death of Muhammad was for 29 years. John J. Pool writes in "Studies in Mohammadanism" (p. 62) that, "The death of Ali was an epoch-making event. We come now to the parting of ways. Henceforward, the Commander of the Faithful ceased to be elected by the votes of the people of Medina or Mecca. Arabia was no longer to be the seat of temporal power. For the future, in Islam might was to take the place of right."