Augustine of Hippo

He says, While men slept, for while the heads of the Church were abiding in supineness, and after the Apostles had received the sleep of death, then came the Devil and sowed upon the rest those whom the Lord in His interpretation calls evil children. But we do well to enquire whether by such are meant heretics, or Catholics who lead evil lives. That He says, that they were sown among the wheat, seems to point out that they were all of one communion. …

Catena Aurea by Aquinas ↗

Jerome

Understand that the men who are asleep are the leaders of the Churches. Do not welcome servants of the household of the father except for the angels, who daily see the Father's face (Matt. XVIII). But the devil is called the enemy of man because he stopped being God. And it is written of him in the ninth psalm: Arise, O Lord, let not man prevail (Psalm IX, 20). Therefore, let the one who is placed over the Church not sleep, lest through his negligence the enemy sows weeds, that is, the dogmas of heretics.

Commentary on Matthew ↗

Thomas Aquinas

But while men were asleep etc. Having treated the origin of good, here he treats of the origin of evil. And first the occasion of the evil inflicted is set down; secondly, the manner. And first a twofold occasion is set down: one on the part of the guardians, the second on the part of the sower. On the part of the guardians he says, but while men were asleep etc., i.e., the overseers of the human race, who were appointed to guard, were sleeping, namely, by the sleep of death. …

Commentary on Matthew ↗