Leviticus 4:7-8

7The kohen shall put some of the blood on the horns of the altar of sweet incense before Adonai, which is in the Tent of Meeting, and he is to pour out all of rest of the blood of the bull at the base of the altar of burnt offering, which is at the entrance of the Tent of Meeting.

8He is to take all the fat of the bull of the sin offering off of it, the fat that covers the innards, all the fat that is on the entrails,