Oecumenius

But now the seal is set, and the prophet, foreseeing in spirit, said: "The light of your face, Lord, has been marked upon us." (Ps. 4:6) It is well, then, that no one be wronged until those worthy of salvation among the Jews are sealed, so that the righteous do not suffer alongside the unwilling sinners.

Commentary on Revelation ↗

Cyprian

And how great, too, are those things which in the meantime are happening in that respect on our behalf! Something is given for an example, that the anger of an avenging God may be known. But the day of judgment is still future which the Holy Scripture denounces, saying, "Howl ye, for the day of the Lord is at hand, and destruction from God shall come; for, lo, the day of the Lord cometh, cruel with wrath and anger, to lay the earth desolate, and to destroy the sinners out of it." And again: "Behold, the day of the Lord cometh, …

Treatise V An Address to Demetrianus ↗

Bede

Until we have sealed the servants of our God on their foreheads? For this reason, the dominion of the nations has been broken, so that the faces of the saints could be freely marked with the sign of faith, to which they had resisted. For the very shape of the cross signifies the Lord's kingdom extended everywhere, as the ancient saying proves: Look at the world divided into four distinct parts, to prove that the kingdom of faith holds all things.

Commentary on Revelation ↗

Bonaventure

How can this be? See what is said toward the end of the Apocalypse. Toward the middle, it is said: "I saw the Lamb standing upon Mount Sion, and with Him a hundred and forty-four thousand having His name and the name of His Father written on their foreheads." But at the opening of the sixth seal, it is said in the Apocalypse: "And I saw another angel ascending from the rising of the sun, having the seal of the living God; and he cried with a loud voice to the four angels, who had it in their power to harm the earth and the sea, …

Collations on the Hexaemeron, Collation 23 ↗