Genesis 39:5 KJV
And it came to pass from the time that he had made him overseer in his house, and over all that he had, that the LORD blessed the Egyptian's house for Joseph's sake; and the blessing of the LORD was upon all that he had in the house, and in the field.
Joseph had been sold by his brothers, carted off to Egypt and bought by Potiphar. He had every reason to be depressed despondent and downright bitter. Who would have blamed him if he had determined that his role was to make the life of a slave owner miserable? He could not change his circumstances but he, he might have reasoned, could help generations to come by setting an example and refusing to work as a slave.
Joseph took a different tact and it was one blessed by God. He chose instead to be a model slave. He chose to be honest, to work well and to help his master prosper. It is here that the Bible says God blessed his master's house for Joseph's sake.
My question is, could the same thing be said of us? Would we even want God to bless a person, a people or a purpose we view as enemies, let alone that He do it on our account? God blessed Nineveh for Jonah's sake but Jonah wasn't happy about it.
We are our best testimony when we are a blessing to everyone and leave vengeance and retribution in the hands of the Lord.