Gregory the Great
Catena Aurea · Matthäusevangelium 3
But when he saw many of the Pharisees and Sadducees come to his baptism, he said unto them, O generation of vipers, who hath warned you to flee from the wrath to come? Bring forth therefore fruits meet for repentance: 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. And now also the axe is laid unto the root of the trees: therefore every tree which bringeth not forth good fruit is hewn down, and cast into the fire.
(Hom. in Ev. xx. 9.) Or, the axe signifies the Redeemer, who as an axe of haft and blade, so consisting of the Divine and human nature, is held by His human, but cuts by His Divine nature. And though this axe be laid at the root of the tree waiting in patience, it is yet seen what it will do; for each obstinate sinner who here neglects the fruit of good works, finds the fire of hell ready for him. Observe, the axe is laid to the root, not to the branches; for that when the children of wickedness are removed, the branches only of the unfruitful tree are cut away. But when the whole offspring with their parent is carried off, the unfruitful tree is cut down by the root, that there remain not whence the evil shoots should spring up again.