Isaiah 60:20
Thy sun shall no more go down; neither shall thy moon withdraw itself: for the LORD shall be thine everlasting light, and the days of thy mourning shall be ended. Thy sun shall no more go down; neither shall thy moon withdraw itself: for the LORD shall be thine everlasting light, and the days of thy mourning shall be ended.
The promise pictures the redeemed dwelling in the city of God, free from sin and from every mark of the curse. That city is seen after victory and after the receiving of the inheritance. There violence and destruction are gone, with walls called Salvation and gates called Praise.
The Lord Himself will be the everlasting light and glory of His people. The sun no more going down and the moon no more withdrawing means sun and moon are no longer needed for light by day or by night. Because Christ reigns forever as the sun and scatters night away, one eternal day shines over the wide, extended plains of the promised home. The ending of the days of mourning means sorrow is finished forever. All the people there are righteous, inheriting the land forever as the planting of the Lord for His glory.
The verse belongs to words of encouragement for those called to take part in God's work on earth. It is a charge to leaders in the cause and to those connected with institutions, given with chapters 60 through 65 as reproof for disregarding reproofs, choosing only part of the word, failing in thorough consecration, and neglecting the duty to warn the people as to what is truth. It is to be heeded, accepted, and studied, and with chapters 61 and 62 through 65 to be understood so that it speaks in a most decided manner.
When its words are taken and all complaining and every evil work are stopped, the Lord manifests His power in the conviction and conversion of souls, and many unwarned souls hear the reasons of faith. The chapter including this promise is to be heeded and accepted by those carrying responsibility, and it is understood when reformation comes to the people of God. Taking its words with stopping complaining and evil working, putting away evil works, and repenting and being converted, brings the appearing of the Lord for the conviction and conversion of souls.