2 Kings 5:10, 12-13

But Elisha sent a messenger out to him with this message: “Go and wash yourself seven times in the Jordan River. Then your skin will be restored, and you will be healed of your leprosy.”

Aren’t the rivers of Damascus, the Abana and the Pharpar, better than any of the rivers of Israel? Why shouldn’t I wash in them and be healed?” So Naaman turned and went away in a rage. 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!’”