`Sayyiduna Abu Hurairah (may Allah be pleased with him) reports that the Messenger of Allah (peace and blessings of Allah be upon him) said: The Hour will not be established until two great groups (of Muslims) fight each other, and there will be a severe battle between them, and both will have the same claim (i.e., both will have the same religion and both will claim that they are fighting for the religion of Allah).