Charles Ellicott Commentary Isaiah 60:19

"The sun shall be no more thy light by day; neither for brightness shall the moon give light unto thee: but Jehovah will be unto thee an everlasting light, and thy God thy glory." — Isaiah 60:19 (ASV)

The sun shall be no more ... —The ideal picture becomes bolder and more transcendent. Sun and moon may still shine, but, as in Revelation 21:23 (obviously derived from this), they shall not be needed in the radiance of the greater glory of the presence of Jehovah. Here on earth the sun sets and the moon wanes, but in that Divine glory there is no waning and no setting. “Mourning” will belong to the past , everlasting joy to the future.