Charles Ellicott Commentary Leviticus 6:4

"then it shall be, if he hath sinned, and is guilty, that he shall restore that which he took by robbery, or the thing which he hath gotten by oppression, or the deposit which was committed to him, or the lost thing which he found," — Leviticus 6:4 (ASV)

Then it shall be, because he hath sinned, and is guilty. —Better, And it shall come to pass, when he has so sinned, and acknowledged his guilt. (See Leviticus 4:22.) That is, when he has committed any of the aforementioned offenses, and denied the sin with an oath, but afterwards voluntarily acknowledges his guilt without having been found out.

That he shall restore that ... which he hath deceitfully gotten. —Better, then he shall restore, etc.