Sahih Bukhari
Hunting, Slaughtering
Volume: 007 / Book Number: 067 / Hadith Number: 447
Narrated Az-Zhuri:
regarding an animal, e.g., a mouse or some other animal that had fallen into solid or liquid oil or butter-fat: I had been informed that a mouse had died in butter-fat whereupon Allah's Apostle ordered that the butter-fat near it be thrown away and the rest of the butter-fat can be eaten.