Jessica, I have this as an arrangement of a plainsong (shows at top of manuscript with square notes and no bar lines). The arrangement is done by Maurice Durufle 1902-1986.

Ubi caritas et amor, Deus ibi est. 2x
Congregavit nos in unum Christi amor. 2x
Exsultemus et in ipso jucundemur.
Timeamus et amemus Deum vivum.
Et ex corde diligamus nos sincero. 2x
Ubi caritas et amor, Deus ibi est. Amen.

If that's not all verses, sorry. That's all I have.
Blessings,
Barbara