Leviticus 6:7-11

and the priest shall make atonement for him before the Lord, and he will be forgiven for any one of the things which he may have done to incur guilt.” The Priest’s Part in the Offerings

Then the Lord spoke to Moses, saying,

“Command Aaron and his sons, saying, ‘This is the law for the burnt offering: the burnt offering itself shall remain on the hearth on the altar all night until the morning, and the fire on the altar is to be kept burning on it.

The priest is to put on his linen robe, and he shall put on linen undergarments next to his body; and he shall take up the fatty ashes to which the fire reduces the burnt offering on the altar and place them beside the altar.

Then he shall take off his garments and put on other garments, and carry the fatty ashes outside the camp to a clean place.