Leviticus 16:15; Leviticus 16:34

15 "Then he shall kill the goat of the sin offering that is for the people and bring its blood inside the veil and do with its blood as he did with the blood of the bull, sprinkling it over the mercy seat and in front of the mercy seat.

34 And this shall be a statute forever for you, that atonement may be made for the people of Israel once in the year because of all their sins." And Moses did as the LORD commanded him.