Adam Clarke on Numbers 5:7

Shall confess their sin - Without confession or acknowledgment of sin, there was no hope of mercy held out.

He shall recompense - For without restitution, in every possible case, God will not for give the iniquity of a man's sin. How can any person in a case of defraud, with his neighbor's property in his possession, expect to receive mercy from the hand of a just and holy God? See this subject considered in the notes on Gen 42:38 (note).