Mukhtasar Sahih Bukhari — Hadith 2191

Abu Huraira (may Allah be pleased with him) narrates from the Messenger of Allah (peace and blessings of Allah be upon him) that he said: "No Muslim should point a weapon at his (Muslim) brother (not even in jest), for he does not know, perhaps Satan may cause the weapon to go off from his hand, and (as a result of killing a Muslim) he may fall into a pit of Hell."