Oecumenius

Therefore, he says that these are the ones who come out of the great tribulation; for the righteous did not only endure a considerable struggle but also a very great one under the dominion of the Antichrist. And it says that they washed their robes and made them white in the blood of the Lamb; indeed, it was more fitting for the robes dyed in blood to become crimson rather than white. How then have they become white? Because baptism, which is accomplished through the death of the Lord, as it seems to the most wise Paul (Rom. …

Commentary on Revelation ↗

Cyprian

And that I might not extend my discourse, beloved brother, to too great a length, and fatigue my hearer or reader by the abundance of a too diffuse style, I have made a compendium; so that the titles being placed first, which every one ought both to know and to have in mind, I might subjoin sections of the Lord's word, and establish what I had proposed by the authority of the divine teaching, in such wise as that I might not appear to have sent you my own treatise so much, as to have suggested material for others to discourse on; a …

Treatise XI Exhortation to Martyrdom Addressed to Fortunatus ↗

Bede

Martyrs wash their robes in the blood of the Lamb, while as for their members, which "seem to the eyes of the ignorant" [to be] defiled by the squalor of their pains, they instead have made [these members] clean of all contagion by their blood which is poured forth for Christ. In addition, they have rendered [their members] worthy of the blessed light of immortality, which is [the meaning of] their having made their washed robes white in the blood of the Lamb.

Homilies on the Gospels 1.10 ↗