Leviticus 16:33-34

and he shall make an atonement for the holy sanctuary, and he shall make an atonement for the tabernacle of the congregation, and for the altar, and he shall make an atonement for the priests, and for all the people of the congregation. And this shall be an everlasting statute unto you, to make an atonement for the children of Israel for all their sins once a year. And he did as the LORD commanded Moses.