Leviticus 1:5

1:5 Then the one presenting the offering must slaughter the bull before the Lord, and the sons of Aaron, the priests, must present the blood and splash the blood against the sides of the altar which is at the entrance of the Meeting Tent.

Leviticus 1:8

1:8 Then the sons of Aaron, the priests, must arrange the parts with the head and the suet on the wood that is in the fire on the altar.