2 Kings 5:13-15

But his officers tried to reason with him and said, “Sir, if the prophet had told you to do something very difficult, wouldn’t you have done it? So you should certainly obey him when he says simply, ‘Go and wash and be cured!’” So Naaman went down to the Jordan River and dipped himself seven times, as the man of God had instructed him. And his skin became as healthy as the skin of a young child, and he was healed! Then Naaman and his entire party went back to find the man of God. They stood before him, and Naaman said, “Now I know that there is no God in all the world except in Israel. So please accept a gift from your servant.”