7 And seeing many of the Pharisees and Sadducees coming to his baptism, he said to them: Ye brood of vipers, who hath shewed you to flee from the wrath to come? 8 Bring forth therefore fruit worthy of penance. 9 And think not to say within yourselves, We have Abraham for our father. For I tell you that God is able of these stones to raise up children to Abraham.
Pseudo-Chrysostom: Stone is hard to work, but when wrought to some shape, it loses it not; so the Gentiles were hardly brought to the faith, but once brought they abide in it for ever.
Jerome: “These stones” signify the Gentiles because of their hardness of heart. See Ezekiel, “I will take away from you the heart of stone, and give you the heart of flesh.” Stone is emblematic of hardness, flesh of softness.
10 For now the axe is laid to the root of the trees. Every tree therefore that doth not yield good fruit, shall be cut down, and cast into the fire.
Rabanus: There are four sorts of tree; the first totally withered, to which the Pagans may be likened; the second, green but unfruitful, as the hypocrites; the third, green and fruitful, but poisonous, such are heretics; the fourth, green and bringing forth good fruit, to which are like the good Catholics.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. I (London: Rivington, 1842).