Leviticus 4:11-12

4:11 But the hide of the bull, all its flesh along with its head and its legs, its entrails, and its dung – 4:12 all the rest of the bull – he must bring outside the camp to a ceremonially clean place, to the fatty ash pile, and he must burn it on a wood fire; it must be burned on the fatty ash pile.

Leviticus 4:21

4:21 He must bring the rest of the bull outside the camp and burn it just as he burned the first bull – it is the sin offering of the assembly.