Albert Barnes Commentary 2 Kings 5:6

"And he brought the letter to the king of Israel, saying, And now when this letter is come unto thee, behold, I have sent Naaman my servant to thee, that thou mayest recover him of his leprosy." — 2 Kings 5:6 (ASV)

That you may recover him - literally, “And you shall recover him.” The Syrian king presumes that, if there is a cure for leprosy to be found in Israel, the way to obtain it will be well known to his royal brother.