Leviticus 16:18

“Aaron shall make atonement on its horns once a year; he shall make atonement on it with the blood of the sin offering of atonement once a year throughout your generations. It is most holy to Yahweh.”

‘The priest shall also put some of the blood on the horns of the altar of fragrant incense which is before Yahweh in the tent of meeting; and all the blood of the bull he shall pour out at the base of the altar of burnt offering which is at the doorway of the tent of meeting.

and one male goat for a sin offering to make atonement for you.

“The priest shall take some of the blood from the sin offering and put it on the door posts of the house, on the four corners of the ledge of the altar, and on the posts of the gate of the inner court.

but into the second, only the high priest enters once a year, not without taking blood, which he offers for himself and for the sins of the people committed in ignorance.