Leviticus 4:25-27

²⁵And the priest shall put some of the blood of the sin offering with his finger on the horns of the altar of whole burnt offering; and he shall pour out all its blood by the bottom of the altar of whole burnt offerings.

²⁶And he shall offer up all his fat on the altar, as the fat of the sacrifice of peace offering; and the priest shall make atonement for him concerning his sin, and it shall be forgiven him.

²⁷And if a soul of the people of the land should sin unwillingly, in doing a thing contrary to any of the commandments of the Lord, which ought not to be done, and shall transgress,