Numbers 15:25, 28

So the priest shall make atonement for the whole congregation of the children of Israel, and it shall be forgiven them, for it was unintentional; they shall bring their offering, an offering made by fire to the LORD, and their sin offering before the LORD, for their unintended sin.

So the priest shall make atonement for the person who sins unintentionally, when he sins unintentionally before the LORD, to make atonement for him; and it shall be forgiven him.