Genesis 37:36

and the Midianites sold him (Joseph) in to Egypt unto Potiphar, an officer of Pharaoh's and captain of the guard. As a slave he was sold to this eunuch, or officer, of the Egyptian king, who was the commander or captain of Pharaoh's body-guard, and incidentally the head-executioner. Joseph is a type of Jesus Christ, the only-begotten Son of the heavenly Father, sent down from heaven for the welfare of His brethren on earth. He also was sold for a few pieces of silver and subjected to every form of indignity. But in all these things, God's gracious counsel of salvation was carried out.