Leviticus 16:16-18

16He will make atonement for the most holy place in this way for all their sins because of the Israelites’ impurities and rebellious acts. He will do the same for the tent of meeting that remains among them, because it is surrounded by their impurities.

17No one may be in the tent of meeting from the time he enters to make atonement in the most holy place until he leaves after he has made atonement for himself, his household, and the whole assembly of Israel.

18Then he will go out to the altar that is before the Lord and make atonement for it. He is to take some of the bull’s blood and some of the goat’s blood and put it on the horns on all sides of the altar.