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

And Aaron shall present the bullock of the sin-offering, which is for himself, and make atonement for himself, and for his house. And he shall take the two goats, and set them before Jehovah at the door of the tent of meeting. And Aaron shall cast lots upon the two goats; one lot for Jehovah, and the other lot for Azazel. And Aaron shall present the goat upon which the lot fell for Jehovah, and offer him for a sin-offering. But the goat, on which the lot fell for Azazel, shall be set alive before Jehovah, to make atonement for him, to send him away for Azazel into the wilderness. And Aaron shall present the bullock of the sin-offering, which is for himself, and shall make 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, even all their sins; and he shall put them upon the head of the goat, and shall send him away by the hand of a man that is in readiness into the wilderness: and the goat shall bear upon him all their iniquities unto a solitary land: and he shall let go the goat in the wilderness.

And it shall be a statute for ever unto you: in the seventh month, on the tenth day of the month, ye shall afflict your souls, and shall do no manner of work, the home-born, or the stranger that sojourneth among you: for on this day shall atonement be made for you, to cleanse you; from all your sins shall ye be clean before Jehovah.

And this shall be an everlasting statute unto you, to make atonement for the children of Israel because of all their sins once in the year. And he did as Jehovah commanded Moses.