Revelation 14:13: "13 And I heard a voice from heaven saying, 'Write this: Blessed are the dead who die in the Lord from now on.' 'Blessed indeed,' says the Spirit, 'that they may rest from their labors, for their deeds follow them!'"
Philippians 1:21: "For to me to live is Christ, and to die is gain."
Revelation 21:4: "'He will wipe away every tear from their eyes, and death shall be no more, neither shall there be mourning, nor crying, nor pain anymore, for the former things have passed away.'"
2 Corinthians 4:16-17: "16 So we do not lose heart. Though our outer self is wasting away, our inner self is being renewed day by day. 17 For this light momentary affliction is preparing for us an eternal weight of glory beyond all comparison"
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The text is public domain:
Oh, how blest are they whose toils are ended,Who through death have unto God ascended!They have arisenFrom the cares which keep us still in prison.We are still as in a dungeon living,Still oppressed with sorrow and misgiving;Our undertakingsAre but toils and troubles and heartbreakings.They meanwhile are in their chambers sleeping,Quiet and set free from all their weeping;No cross or sadnessThere can hinder their untroubled gladness.Christ has wiped away their tears forever;They have that for which we still endeavor.By them are chantedSongs that ne'er to mortal ears were granted.Come, O Christ, and loose the chains that bind us;Lead us forth and cast this world behind us.With You, the Anointed,Finds the soul its joy and rest appointed.
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Revelation 14:13 is paraphrased as "Oh, how blest are they whose toils are ended, / Who through death have unto God ascended!" This seems to incorporate "to die is gain" from Philippians 1:21 too. The rest in Revelation 14:13 is referred to at the end of the hymn ("With You, the Anointed, / Finds the soul its joy and rest appointed").
2 Corinthians 4:16-17 seems to appear in the contrast between the second and third verses.
Revelation 21:4 appears in most of the third verse and at the beginning of the fourth verse.