Mukhtasar Muslim

Abu Huraira (may Allah be pleased with him) reports that the Messenger of Allah (peace and blessings be upon him) said: The anger of Allah is very severe upon those who do such a thing, and the Prophet (peace and blessings be upon him) would point towards his tooth, and said: The anger of Allah is also very severe upon the person whom the Messenger of Allah (peace and blessings be upon him) kills in the way of Allah (i.e., in jihad, because that wretched person must have intended to kill the Prophet, and this does not refer to those whom the Prophet (peace and blessings be upon him) killed as a legal punishment or in retribution).