Leviticus 5:16
And he shall make amends for the harm that he has done in the holy thing, and shall add the fifth part thereto, and give it to the priest: and the priest shall make an atonement for him with the ram of the trespass offering, and it shall be forgiven him.
Torrey's Topical Textbook—AKJV

Leviticus 6:5
Or all that about which he has sworn falsely; he shall even restore it in the principal, and shall add the fifth part more thereto, and give it to him to whom it appertains, in the day of his trespass offering.
Torrey's Topical Textbook—AKJV