Leviticus 16:1-6

¹And the Lord said to Moses, after the death of the two sons of Aaron when they took in strange fire before the Lord and death overtook them;

²The Lord said to Moses, Say to Aaron, your brother, that he may not come at all times into the holy place inside the veil, before the cover which is on the ark, for fear that death may overtake him; for I will be seen in the cloud on the cover of the ark.

³Let Aaron come into the holy place in this way: with an ox for a sin-offering and a male sheep for a burned offering.

⁴Let him put on the holy linen coat, and the linen trousers on his body, and the linen band round him, and the linen head-dress on his head; for this is holy clothing, and before he puts them on his body is to be washed with water.

⁵And let him take from the children of Israel two he-goats for a sin-offering and one male sheep for a burned offering.

⁶And Aaron is to give the ox of the sin-offering for himself, to make himself and his house free from sin.