Oecumenius

And He made them kings and priests to our God, and they shall reign on the earth. Therefore, you are able also to understand the Scripture, for you are faithful servants of Christ, both kings and leaders of the churches; you are able to govern the passions rather than be governed by them; and as priests, you bring your own bodies "as a living, holy, and acceptable sacrifice to God," according to what is written. (Rom. 12:1)

Commentary on Revelation ↗

Hippolytus of Rome

And thou shalt receive the kingdom of heaven, thou who, whilst thou didst sojourn in this life, didst know the Celestial King. And thou shalt be a companion of the Deity, and a co-heir with Christ, no longer enslaved by lusts or passions, and never again wasted by disease. …

Hippolytus Refutation of All Heresies Book X ↗

Alcuin of York

And hast made us to our God a kingdom and priests, and we shall reign on the earth. The elect are kings, when, by restraining their bodies, it is as if they were reigning over a subjected earth with the law of virtue, which is why they affirm they have received a kingdom on earth too. They are priests because they offer themselves to God by chastising themselves every day, according to this: A sacrifice to God is an afflicted spirit. [Ps. 50:19]

Commentary On Revelation ↗