14 And the four beasts said, Amen. And the four and twenty elders fell down and worshipped him that liveth for ever and ever.
[AD 990] Oecumenius on Revelation 5:13-14
The present words show the concordant hymn of praise from all creation in heaven and on earth to God, both the Father and the Word incarnate in human form, with the Holy Spirit, too, of course, sharing in their praise.

[AD 614] Andreas of Caesarea on Revelation 5:14
Through these, one flock and one church from angels and from men is indicated which has been formed through Christ, the God who united that which was separate and has destroyed the partition wall of separation. And so, as we have heard, with the four living creatures who surpass the other angelic ranks, also the [elders], who represent the fullness of those who are being saved, are worthy of the hymn and worship of God. Of which may also we be found worthy in Christ himself, the Giver of peace and our God, with whom together with the Father and the Holy Spirit be glory and might forever and ever. Amen.

[AD 735] Bede on Revelation 5:14
And the four living creatures said Amen, etc. As the people in the Church resound with praises to the Lord, the teachers confirm the same and, by the example of their lives, together worship the Lord.