And the city had no need of the sun, neither of the moon, to shine in it - This imagery seems to be derived from Isaiah 9:19-20. See notes on those verses. No language could give a more striking or beautiful representation of the heavenly state than what is here employed.
For the glory of God did lighten it - By the visible splendor of his glory. See the notes on Revelation 21:11. That supplied the place of the sun and the moon.
And the Lamb is the light thereof - The Son of God; the Messiah. See the Revelation 5:6 note; Isaiah 60:19 note.