matthew 3:9 And think not to say within yourselves, We have Abraham to our father: for I say unto you, that God is able of these stones to raise up children unto Abraham. - Free Bible Online

      9. And think not to say within yourselves, We have Abraham to our father--that pillow on which the nation so fatally reposed, that rock on which at length it split.
      for I say unto you, that God is able of these stones to raise up children unto Abraham--that is, "Flatter not yourselves with the fond delusion that God stands in need of you, to make good His promise of a seed to Abraham; for I tell you that, though you were all to perish, God is as able to raise up a seed to Abraham out of those stones as He was to take Abraham himself out of the rock whence he was hewn, out of the hole of the pit whence he was digged" (Isa 51:1). Though the stern speaker may have pointed as he spoke to the pebbles of the bare clay hills that lay around (so STANLEY'S Sinai and Palestine), it was clearly the calling of the Gentiles--at that time stone-dead in their sins, and quite as unconscious of it--into the room of unbelieving and disinherited Israel that he meant thus to indicate (see Mt 21:43; Ro 11:20, 30).

JFB.