Genesis 39:21

In the prison itself Jehovah was with Joseph, procuring him favour in the eyes of the governor of the prison, so that he entrusted all the prisoners to his care, leaving everything that they had to do, to be done through him, and not troubling himself about anything that was in his hand, i.e., was committed to him, because Jehovah made all that he did to prosper. "The keeper" was the governor of the prison, or superintendent of the gaolers, and was under Potiphar, the captain of the trabantes and chief of the executioners (Gen 37:36).

At this chapter we return to the story of Joseph. We have him here, I. A servant, a slave in Potiphar's house (Gen 39:1), and yet there greatly honoured and favoured, I. By the providence of God, which made him, in effect, a master (Gen 39:2-6). 2. By the grace of God, which made him more than a conqueror over a strong temptation to uncleanness (Gen 39:7-12). II. We have him here a sufferer, falsely accused (Gen 39:13-18), imprisoned (Gen 39:19, Gen 39:20), and yet his imprisonment made both honourable and comfortable by the tokens of God's special presence with him (Gen 39:21-23). And herein Joseph was a type of Christ, "who took upon him the form of a servant," and yet then did that which made it evident that "God was with him," who was tempted by Satan, but overcame the temptation, who was falsely accused and bound, and yet had all things committed to his hand.

39:21-23 Joseph thrived in prison because God was with him. Each time Joseph prospered, he was put in charge of something.