From Sahih Bukhari (Hadith 5539):
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 Messenger (ﷺ) ordered that the butter-fat near it be thrown away and the rest of the butter-fat can be eaten
Reference: Bukhari 5539