Leviticus 16:29-34

“On the tenth day of the appointed month in early autumn, you must deny yourselves. Neither native-born Israelites nor foreigners living among you may do any kind of work. This is a permanent law for you. On that day offerings of purification will be made for you, and you will be purified in the LORD’s presence from all your sins. It will be a Sabbath day of complete rest for you, and you must deny yourselves. This is a permanent law for you. In future generations, the purification ceremony will be performed by the priest who has been anointed and ordained to serve as high priest in place of his ancestor Aaron. He will put on the holy linen garments and purify the Most Holy Place, the Tabernacle, the altar, the priests, and the entire congregation. This is a permanent law for you, to purify the people of Israel from their sins, making them right with the LORD once each year.” Moses followed all these instructions exactly as the LORD had commanded him.