Verse 3. - And his master saw that the Lord (Jehovah) was with him - this does not imply that Potiphar was acquainted with Jehovah, but simply that he concluded Joseph to be under the Divine protection - and that the Lord (Jehovah) made all that he did to prosper in his hand. That which led to the conviction of Potiphar concerning Joseph was the remarkable success which he saw attending all his efforts and undertakings.

39:1-6 Our enemies may strip us of outward distinctions and ornaments; but wisdom and grace cannot be taken from us. They may separate us from friends, relatives, and country; but they cannot take from us the presence of the Lord. They may shut us from outward blessings, rob us of liberty, and confine us in dungeons; but they cannot shut us out from communion with God, from the throne of grace, or take from us the blessings of salvation. Joseph was blessed, wonderfully blessed, even in the house where he was a slave. God's presence with us, makes all we do prosperous. Good men are the blessings of the place where they live; good servants may be so, though mean and lightly esteemed. The prosperity of the wicked is, one way or other, for the sake of the godly. Here was a wicked family blessed for the sake of one good servant in it.And his master saw that the Lord was with him,.... He knew nothing of the spiritual and gracious presence of God that was with him, he was no judge of that; but he perceived by the ingenuity of his mind, by his ready and speedy learning the Egyptian language, by his dexterity in business, and by the prudence and faithfulness with which he did everything, that he was highly favoured by the divine Being, and had great endowments bestowed upon him, and was an extraordinary person for his age:

and that the Lord made all that he did to prosper in his hand; and though Potiphar might have no knowledge of the true Jehovah, whose name he uses, yet he might have a notion of a supreme Being, and that all outward prosperity was owing to him; and knowing Joseph to be an Hebrew, as it is plain his wife did, Genesis 39:14; and Jehovah to be the God of the Hebrews, he imputes all the prosperity that attended Joseph and his services unto his God.