Revelation 21:5 (ESV) … “And he who was seated on the throne said, “Behold, I am making all things new.” Also he said, “Write this down, for these words are trustworthy and true.”
In chapter 21 the first speaker was an unidentified voice from the throne. John now hears a second speaker. The throne is the great throne of heaven, first seen in 4:2, but most recently the place of final judgment (20:11). The Judge of the final reckoning was Christ. Now he speaks, as Creator rather than as Judge. Isaiah had foreseen this new creation (Isa. 65:17). During his earthly life Jesus had pledged, “I am going there [to my Father’s house] to prepare a place for you” (John 14:2), suggesting a process of creation. Now his statement that I am making everything new emphasizes both the process and settled determination of Jesus to establish this eternal reality.
The angel in charge of this vision had commanded John earlier to write a “blessed” followed by a solemn affirmation of its divine trustworthiness (19:9). Now Jesus himself urges John to write this down, apparently the entire vision sequence. An equally solemn affirmation follows, applying especially to the words just spoken. They are trustworthy and true words because they issue from the one whose name is “Faithful and True” (19:11; the vocabulary is identical in the original).
Most people like to move into a brand new home; one day we shall move into a brand new world. It will indeed be a splendid place in which to live, for God will lavish the genius of His creative imagination upon it and will furnish it from resources of His unlimited power. It will take instant shape. He says, Behold I make all things new, and in the next breath He says, It is done! He is the beginning and the ending; there is no need for anything more between. It will not take the countless ages of an imagined evolutionary process to bring that world into being. He who said in the early dawn of time, “Light, be!!”—and light was! will again put forth His power and a new universe will appear. We cannot imagine what it will be like. Even this present world, marred and spoiled as it is by sin, contains scenes of beauty that take our breath away. The landscapes of glory will be better far than these.
 Easley, K. H. (1998). Revelation (Vol. 12, pp. 395–396). Nashville, TN: Broadman & Holman Publishers.  Phillips, J. (2009). Exploring Revelation: An Expository Commentary (Re 21:5–8). Kregel; WORDsearch Corp.