Leviticus 4:7-8

7Then the priest will put some of the blood on the horns of the altar for sweet-smelling incense in the Lord’s presence in the tent of meeting. He will pour the rest of the bull’s blood at the bottom of the altar for burnt offerings at the entrance to the tent of meeting.

8He will remove all of the fat from the bull that is the offering for sin, the fat that covers the internal organs,