Leviticus 4:25-27

²⁵And the priest shall take some of the blood of the sin-offering with his finger, and put it upon the horns of the altar of burnt-offering; and the remainder of its blood shall he pour out at the bottom of the altar of burnt-offering.

²⁶And all its fat shall he burn upon the altar, as the fat of the sacrifice of peace-offering; and the priest shall make an atonement for him concerning his sin, and it shall be forgiven unto him.

²⁷And if any person of the common people should sin through ignorance, by his doing any one of the prohibitions of the Lord, which ought not to be done, and become guilty;