John 9:30

30.Certainly this is wonderful. He indirectly reproves them for remaining unmoved by a miracle so illustrious, and for pretending that they did not know Christ’s calling; as if he had said, that it was highly improper that such a testimony of Divine power should be held in no estimation, and that the calling of Christ, so proved and attested, should obtain no credit among them. And, in order to show more clearly their stupidity or malice, he magnifies the excellence of the miracle from this consideration, that, as far as the memory of men reaches, none was ever heard to say that such a thing was done by a man. Hence it follows that they are malicious and ungrateful, because they voluntarily shut their eyes on a manifest work of God. He infers from this, that Christ was sent by God, because he is endued with so great power of the Spirit of God, to procure credit for himself and for his doctrine.