Leviticus 16:7-10

Then he shall take the two goats and set them before the LORD at the entrance of the tent of meeting. And Aaron shall cast lots over the two goats, one lot for the LORD and the other lot for Azazel. And Aaron shall present the goat on which the lot fell for the LORD and use it as a sin offering, but the goat on which the lot fell for Azazel shall be presented alive before the LORD to make atonement over it, that it may be sent away into the wilderness to Azazel.