John the Apostle
Revelation 21:5BSB·traditional attribution

And the One seated on the throne said, “Behold, I make all things new.” Then He said, “Write this down, for these words are faithful and true.”

Matthew Henry Presbyterian @wholebiblehenry

We have here a more general account of the happiness of the church of God in the future state, by which it seems most safe to understand the heavenly state. I. A new world now opens to our view (Rev 21:1): I saw a new heaven and a new earth; that is, a new universe; for we suppose the world to be made up of heaven and earth.

Commenting on Revelation 21:1-8

John Gill Reformed Baptist @doctorgill

And he that sat upon the throne said,.... By whom is meant, either God the Father, who is often represented in this book as sitting on the throne, and as distinguished from Christ the Lamb; see Rev 4:2 Rev 5:13 and who may seem the more to be intended, since he is by adopting grace the God and Father of his people, and they are...

Albert Barnes Presbyterian @notesbybarnes

Verse 5. And he that sat upon the throne said. Probably the Messiah, the dispenser of the rewards of heaven. . Behold, I make all things new. A new heaven and new earth, (,) and an order of things to correspond with that new creation. The former state of things when sin and death reigned will be changed, and the change consequent on this must extend to everything.