I said, "O LORD, have mercy on me; heal me, for I have sinned against you."

What? Why? Why would he ask that? 'Lord, heal me cuz I sinned.' I mean, that doesn't even make a tiny little nip of sense, if you think about it. Or maybe he was crying for mercy. 'Lord, I've sinned, please have mercy and heal me' sort of thing. But what it really sounds like is, ' Heal me because I sinned agianst you.' But I don't know. Any help?