Leviticus 16:23-25

23Then Aaron is to enter the Tent of Meeting, take off the linen garments he put on before entering the Most Holy Place, and leave them there. 24He is to bathe himself with water in a holy place and put on his own clothes. Then he must go out and sacrifice his burnt offering and the people’s burnt offering to make atonement for himself and for the people. 25He is also to burn the fat of the sin offering on the altar.