To whom shall I speak...? — The prophet, who now speaks in his own name, has heard the message from the Lord of Hosts; but what avails it? who will listen? As elsewhere the lips (Exodus 6:30) and the heart (Leviticus 26:41; Ezekiel 44:7), so here the ear of Israel was uncircumcised, as though it had never been brought into covenant with Jehovah or consecrated to His service.
A reproach. — i.e., the object of their scorn.