Musnad Ahmad 28:118

Hassan ibn Musa narrated to us, Ibn Lahi'ah narrated to us, Abu Qabil informed us, from Malik ibn Abdullah, from Abdullah ibn Amr ibn al-Aas: "That the Messenger of Allah, may Allah bless him and grant him peace, used to seek refuge from seven deaths: sudden death, the sting of a snake, the beast of prey, burning, drowning, falling from something or having something fall upon him, and killing at the time of fleeing from the battlefield."