John Calvin Commentary Genesis 31:49

"and Mizpah, for he said, Jehovah watch between me and thee, when we are absent one from another." — Genesis 31:49 (ASV)

The Lord watch between me and you. Laban commits to the judgment of God, for vengeance, whatever offense either of them should be guilty of against the other in his absence; as if he would say, “Though the knowledge of the injury should not reach me, because I will be far distant, yet the Lord, who is everywhere present, will behold it.” Which sentiment he more clearly expresses afterwards, when he says, “No one is with us; God will be witness between me and you.” By which words he means, that God will be a severe avenger of every wickedness, though there should be no judge on earth to decide the cause.

And certainly if there were any religion flourishing within us, the presence of God would influence us far more than the observation of men. But it arises from the brutal stupidity of our flesh, that we reverence men only; as if we might mock God with impunity, when we are not convicted by the testimony of men.

If, then, this common feeling of nature dictated to Laban, that the frauds which were hidden from men would come into judgment before God; we who enjoy the light of the gospel should indeed be ashamed to seek a cover for our deceptions. From this also, we gather the legitimate use of an oath, which the Apostle declares in his Epistle to the Hebrews; namely, that men, in order to put an end to their controversies, resort to the judgment of God.