Sahih Bukhari
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
Volume: 005 / Book Number: 059 / Hadith Number: 400
Narrated Abu Huraira:
Allah's Apostle (pointing to his broken canine tooth) said, "Allah's Wrath has become severe on the people who harmed His Prophet. Allah's Wrath has become severe on the man who is killed by the Apostle of Allah in Allah's Cause."