This is a traditional hymn that is for both Advent (use verse 3) and Epiphany (use verse 4).
It is based on Psalm 72 and written by James Montgomery c19. The tune is CRUGER by Johann Crüger. There are several iterations of the text but I have put the one in CWB II below.
CWB II sets it in Eb which is somewhat lower than most versions and a sensible move.
1. Hail to the Lord’s Anointed,
great David’s greater Son!
Hail in the time appointed,
his reign on earth begun!
He comes to break oppression,
to set the captive free;
to take away transgression,
and rule in equity.2. He comes with help and mercy
to those who suffer wrong;
to raise the poor and needy,
and bid the weak be strong;
to give them songs for sighing,
their darkness turn to light,
whose souls, condemned and dying,
were precious in his sight.3. He shall come down like showers
upon the fruitful earth;
love, joy, and hope, like flowers,
spring in his path to birth.
Before him on the mountains,
shall peace, the herald, go,
and righteousness, in fountains,
from hill to valley flow.4. Kings shall bow down before him,
and gold and incense bring;
All nations shall adore him,
His praise all people sing;
To him shall prayer unceasing
and daily vows ascend;
His kingdom still increasing,
a kingdom without end.5. O’er every foe victorious,
he on his throne shall rest,
From age to age more glorious,
all blessing and all-blest.
The tide of time shall never
his covenant remove;
his name shall stand forever,
that name to us in love.