John Wesley on 2 Samuel 12:1

The Lord sent - When the ordinary means did not awaken David to repentance, God takes an extraordinary course. Thus the merciful God pities and prevents him who had so horribly forsaken God. He said - He prudently ushers in his reproof with a parable, after the manner of the eastern nations, that so he might surprize David, and cause him unawares to give sentence against himself.