Leviticus 16:19

‘You shall also take some of its blood and put it on its four horns and on the four corners of the ledge and on the border round about; thus you shall purify it and make atonement for it.

“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.