Ezekiel 45:18-20

18Thus saith the Lord Jehovah: In the first [month], on the first of the month, thou shalt take a young bullock, without blemish, and thou shalt purge the sanctuary.

19And the priest shall take of the blood of the sin-offering, and put it upon the posts of the house, and upon the four corners of the settle of the altar, and upon the posts of the gate of the inner court.

20So thou shalt do also on the seventh of the month for every one that erreth, and for the simple; and ye shall make atonement for the house.