Virtues and Merits of the Prophet (pbuh) and his Companions

Bukhari :: Book 4 :: Volume 56 :: Hadith 798

Narrated Sasaa:

Abu Said Al-Khudr said to me, "I notice that you like sheep and you keep them; so take care of them and their food, for I have heard Allah's Apostle saying, 'A time will come upon the people when the best of a Muslim's property will be sheep, which he will take to the tops of mountains and to the places of rain-falls to run away with his religion in order to save it from afflictions.' "