Sahih Bukhari
Mortgaging
Volume: 003 / Book Number: 045 / Hadith Number: 689
Narrated Abu Huraira:
Allah's Apostle said, "The mortgaged animal can be used for riding as long as it is fed and the milk of the milch animal can be drunk according to what one spend on it. The one who rides the animal or drinks its milk should provide the expenditures."