John Calvin Commentary Psalms 37:6

"And he will make thy righteousness to go forth as the light, And thy justice as the noon-day." — Psalms 37:6 (ASV)

And he will bring forth thy righteousness as the light. This David says, to anticipate the misgivings that often trouble us when we seem to lose our labor in faithfully serving God and in dealing uprightly with our neighbors; indeed, when our integrity is either exposed to the slander of the wicked or leads to us being harmed by others; for then it is thought to be of no account in the sight of God.

David, therefore, declares that God will not allow our righteousness to be always hidden in darkness, but that He will maintain it and bring it forth to the light; namely, when He will bestow upon us such a reward as we desire. He alludes to the darkness of the night, which is soon dispelled by the dawning of the day; as if he had said, We may often be grievously oppressed, and God may not seem to approve our innocence, yet this adversity should no more disturb our minds than the darkness of the night which covers the earth, for then the expectation of the light of day sustains our hope.