Your sun shall no more go down, nor your moon withdraw itself means God’s people will longer witness the sun setting or the moon waning. It is not clear whether this means the sun and moon will cease to exist, or whether they will continue to exist and never set, always shining. Many versions consulted render these lines in that latter sense. However, if Yahweh himself is to be their light source then light from the sun and moon will not be needed, as in the previous verse. Yahweh has replaced them as sources of light. One possible way to hint at this meaning is not to focus on the sun and moon themselves but rather on the light they give (so Good News Translation). Die Bibel im heutigen Deutsch does this by saying “Therefore your light will never again go down like the sun or diminish like the moon.” The phrase no more occurs here for the third time in this subsection (see verse 18).

For the LORD will be your everlasting light repeats the statement from the previous verse and provides the reason for the demise of the light of the sun and moon (see the comments there). The Hebrew particle ki rendered for is a logical connector here.

And your days of mourning shall be ended: The idea of mourning would be appropriate if these words were addressed to a special audience, those in Jerusalem who have been complaining that Yahweh’s promises had not been fulfilled. But that does not appear to be the context provided in this section, so the sudden appearance of the phrase your days of mourning seems out of place. The possible relationship between light and an end to mourning is unclear. There was a reference to “mourners” in 57.18 to describe the people’s situation, but any possible connection with the statement here is uncertain. However, in 61.1-4 there are references to the difficult situation of the people in Judah, so the theme of mourning is present in these core chapters of Third Isaiah (60–62). Your days of mourning may be understood as a figurative expression for the period of suffering that the people endured when they tried to settle back into their devastated land. Good News Translation places this line at the beginning of the verse and renders your days of mourning as “Your days of grief,” which is a more general description of suffering. Whatever specific reference this phrase might have, the whole line promises that a period of hardship will come to an end. The Hebrew verb rendered shall be ended has the sense of something that is completed. For this line New Jerusalem Bible has “and your days of mourning will be over.”

For the translation of this verse see the following examples:

• The sun that sets over you will do so no more,
and the moonlight will fade no more,
because the LORD himself will be your eternal light,
and your period of mourning will end.

• Your sun will set no more,
and your moon never again wane,
because Yahweh will be your source of eternal light,
and you will no longer be in mourning.

Quoted with permission from Ogden, Graham S. and Sterk, Jan. A Handbook on Isaiah. (UBS Helps for Translators). New York: UBS, 2011. For this and other handbooks for translators see here .