Sahih Bukhari
Afflictions and the End of the World
Volume: 009 / Book Number: 088 / Hadith Number: 210
Narrated Abu Sa'id Al-Khudri:
Allah's Apostle said, "There will come a time when the best property of a Muslim will be sheep which he will take to the tops of mountains and the places of rainfall so as to flee with his religion from the afflictions.