Charles Ellicott Commentary Leviticus 6:5

"or any thing about which he hath sworn falsely; he shall even restore it in full, and shall add the fifth part more thereto: unto him to whom it appertaineth shall he give it, in the day of his being found guilty." — Leviticus 6:5 (ASV)

And shall add the fifth part more thereto. — The first thing the offender must do, when he realizes and confesses his guilt, is to make restitution of the property he had embezzled—if he still has it, or, if that is impossible, to pay its value as estimated by the authorized tribunal. Besides this, the offender is to add a fifth part of the principal to compensate for the loss the owner sustained during the interval.

It will be seen that in Exodus 22:1-9, when a person was guilty of any of the offenses specified here, the offender was condemned to make fourfold restitution. In contrast, in the passage before us, the penalty is reduced to the restitution of the principal with the addition of a fifth part.

The reason for this difference is that the law in Exodus deals with a culprit who is convicted of his crime in a court of justice by means of witnesses. In contrast, the law before us deals with an offender who, through compunction of mind, voluntarily confesses his offense, and whose guilt for this offense could not have been proven without this voluntary confession. It is this difference that constitutes it a case for a trespass offering .

In the day of his trespass offering. — A better rendering is on the day of his guilt. That is, as soon as he acknowledges his guilt and brings the sacrifice for his offense, he is to make the requisite restitution.