Genesis 39:3

3. And his master saw. Here that which has been lately alluded to more clearly appears, that the grace of God shone forth in Joseph, in no common or usual manner; since it became thus manifest to a man who was a heathen, and, in this respect, blind. How much more base is our ingratitude, if we do not refer all our prosperous events to God as their author; seeing that Scripture often teaches us, that nothing proceeding from men, whether counsels, or labors, or any means which they can devise, will profit them, except so far as God gives his blessing. And whereas Potiphar, on this account, conceived so much greater regard for Joseph, as to set him over his house; we hence gather, that heathens may be so affected by religion, as to be constrained to ascribe glory to God. However, his ingratitude again betrays itself, when he despises that God whose gifts he estimates so highly in the person of Joseph. He ought at least to have inquired who that God was, that he might conform himself to the worship due to him: but he deems it enough, insomuch as he thinks it will be for his private advantage, to acknowledge that Joseph was divinely directed, in order that he may use his labor with greater profit.

The lord made all that he did to prosper in his hand. This was a wonderful method of procedure, that the entire blessing by which the Lord was pleased to testify his paternal love towards Joseph, should turn to the gain of the Egyptians. For since Joseph neither sowed nor reaped for himself, he was not at all enriched by his labor. But in this way it was brought about that a proud man, who otherwise might have abused him as a vile and sordid slave, should treat him humanely and liberally. And the Lord often soothes the wicked by such favors, lest when they have suffered any injury, they should turn the fury of their indignation against the pious. We here see how abundantly the grace of God is poured out upon the faithful, since a portion of his kindness flows from them even to the reprobate. We are also taught what an advantage it is to receive the elect children of God to our hospitality, or to join ourselves to those whom the divine favor thus accompanies, that it may diffuse its fragrance to those who are near them. But since it would not greatly profit us to be saturated with those temporal benefits of God, which suffocate and ruin the reprobate; we ought to center all our wishes on this one point, that God may be propitious to us. Far better was it for Joseph that Potiphar’s wealth should be increased for his sake; than it was for Potiphar to make great gain by Joseph.