Leviticus 16:6-11, 21-22, 29-30, 34

And Aaron shall offer his bullock of the sin offering, which is for himself, and make an atonement for himself, and for his house. And he shall take the two goats, and present them before the LORD at the door of the tabernacle of the congregation. And Aaron shall cast lots upon the two goats; one lot for the LORD, and the other lot for the scapegoat. And Aaron shall bring the goat upon which the LORD's lot fell, and offer him for a sin offering. But the goat, on which the lot fell to be the scapegoat, shall be presented alive before the LORD, to make an atonement with him, and to let him go for a scapegoat into the wilderness. And Aaron shall bring the bullock of the sin offering, which is for himself, and shall make an atonement for himself, and for his house, and shall kill the bullock of the sin offering which is for himself

and Aaron shall lay both his hands upon the head of the live goat, and confess over him all the iniquities of the children of Israel, and all their transgressions in all their sins, putting them upon the head of the goat, and shall send him away by the hand of a fit man into the wilderness: and the goat shall bear upon him all their iniquities unto a land not inhabited: and he shall let go the goat in the wilderness.

And this shall be a statute for ever unto you: that in the seventh month, on the tenth day of the month, ye shall afflict your souls, and do no work at all, whether it be one of your own country, or a stranger that sojourneth among you: for on that day shall the priest make an atonement for you, to cleanse you, that ye may be clean from all your sins before the LORD.

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.