Technically, this isn’t a Mormon Christmas hymn — Samuel Medley and John Rippon were both 18th century Englishmen. But this hymn has appeared in LDS hymnals (this scan is from the 1927 Psalmody), and Samuel Medley also wrote the words to “I Know that My Redeemer Lives.”

Mortals, awake! with angels join,
And chant the solemn lay;
Love, joy and gratitude combine,2
To hail th’auspicious day.

In heav’n the rapt’rous song began,
And sweet seraphic fire
Thro’ all the shining legions ran,
And swept the sounding lyre.

The theme, the song, the joy was new
To each angelic tongue;
Swift thro’ the realms of light it flew,
And loud the echo rang.

Down thro’ the portals of the sky
The pealing anthems ran,
And angels flew with eager joy
To bear the news to man.

Hark! the cherubic armies shout,
And glory leads the song;
Peace and salvation swell the note
Of all the heav’nly throng.

With joy the chorus we’ll repeat –
“Glory to God on high;
Good-will and peace are now complete;
Jesus was born to die.”

Hail, Prince of Life, forever hail,
Redeemer, Brother, Friend!
Though earth and time and life should fail,
Thy praise shall never end.