Jesus was asking Peter, “If I am the Son of the One who owns the temple, then am I not free from paying temple tax?” Of course He would be exempt. He would be totally justified in not paying the tax. Yet watch what He says to Simon Peter: Nevertheless, lest we offend them, go to the sea, cast in a hook, and take the fish that comes up first. And when you have opened its mouth, you will find a piece of money; take that and give it to them for Me and you. —MATTHEW 17:27, EMPHASIS ADDED
