say: “A people will emerge from my ummah who recite the Quran. Your recitation will be as nothing compared with theirs (1), your prayer as nothing compared with theirs, and your fasting as nothing compared with theirs. They will recite the Quran, believing it to be in their favor, whereas it will be against them. Their prayers (2) will not pass beyond their collarbones. They will pass clean through Islam just as an arrow passes through its quarry. If the army that confronts them knew what had been decreed for them through the words of their Prophet, they would desist from all other deeds.”
Abū Saʿīd also narrated from the Prophet (peace and blessings be upon him) in this hadith: “They will kill the people of Islam and leave the idolaters alone. If I live to encounter them, I will surely kill them as the people of ʿĀd were killed.” Narrated by al-Bukhārī and Muslim (3).
In another narration by Muslim (4): “My ummah will divide into two factions, and a renegade group will emerge from between them. Whichever of the two factions is closer to the truth will undertake to kill them.”
These were the people whom the Commander of the Faithful, Alī (may Allah be pleased with him), killed when the division (5) arose between the people of Iraq and Syria. They were known as the Harūriyya. The Prophet (peace and blessings be upon him) made clear that both contending factions belonged to his ummah and that Alī’s companions were closer to the truth. He urged fighting only those renegades (6) who had departed Islam, broken away from the Muslim community, and deemed the lives and property of all other Muslims lawful. It is established by the Quran, the Sunnah, and the consensus of the ummah that whoever departs from Islamic law is to be fought, even if he pronounces the two testimonies of faith.