Musannaf Ibn Abi Shayba 37:155

Husayn ibn Ali narrated to us, from Za'idah, from Abdullah ibn Uthman, from Nafi' ibn Sarjas, from Abu Hurayrah, who said: "Tribulations have overshadowed you like pieces of a dark night. The most saved of people in them is the owner of a mountain peak who eats from the milk of his sheep, or a man behind the path, holding the rein of his horse, eating from the edge of his sword."