Abu Bakra reported the Prophet as saying, “When two Muslims meet and one of them bears arms against his brother, they are both on the brink of hell, and if one of them kills the other they will both enter it.” In a version on Abu Bakra's authority he said, “When two Muslims meet with their swords, the one who kills and the one who is killed will go to hell." When he (i.e. Abu Bakr) remarked that one was the killer and asked what was wrong with the one who was killed, he replied, “He was eager to kill his companion."
Jarir reported God’s Messenger as saying at the Farewell Pilgrimage, “You must never revert to infidelity after my death and cut off one another’s heads.”
Anas told that some people of ‘Ukl who had come to the Prophet and accepted Islam found Medina unhealthy, so he ordered them to go to the camels of the sadaqa and drink some of their urine and their milk. They did so and became well, after which they apostatised, killed the herdsmen and drove off the camels. So he sent people in pursuit of them, and when they were brought he had their hands and feet cut off and their eyes put out and left them to die without cauterising them to stop the flow of blood. A version says nails were driven into their eyes. Another says he ordered nails to be heated and after having them blinded with them he had them thrown out on the harra, and although they begged for water they were left to die without being given any.
Abu Sa'id al-Khudri reported God’s Messenger as saying, “My people will be in two sections from among whom a seceding party will go out, and those who are nearest to the truth will undertake the killing of them.”
