John Gills Exposition of the Bible Commentary

Verse 5 (Revelation 22:5)

And there shall be no night there ,.... This is repeated from Revelation 21:25 to express the certainty of it, and to observe, that the happiness of this state will greatly lie in the light thereof; it will be one everlasting day, ημερα αιωνος , "day of eternity", or eternal day, as in 2 Peter 3:18

and they need no candle, nor the light of the sun ; neither artificial nor natural light; neither the dimmer light of the ceremonial law, under the legal dispensation, which was like a candle lighted up in Judea; nor the more clear light of the Gospel and its ordinances, under the present dispensation, which now will be at an end:

for the Lord God giveth them light ; immediately from himself, without the use of means and ordinances; and in his light the saints will see all things clearly; who will be always communicating it to them, and will be their everlasting light; See Gill on Revelation 21:23 .

and they shall reign for ever and ever ; they are made kings now, and in this state they shall reign with Christ for the space of a thousand years; and when they are ended, they shall not cease to reign; nor will Christ, when he delivers up the kingdom to the Father, for his and their kingdom is an everlasting one, Revelation 1:6 and here ends the account of this glorious state of things; what follows is the conclusion of the whole book.

- John Gills Exposition of the Bible Commentary