Eternal Rest
Requiem Aeternam
The Eternal Rest prayer for the dead — 'Eternal rest grant unto them, O Lord' — in traditional English and Latin.
Eternal rest grant unto them, O Lord, and let perpetual light shine upon them. May they rest in peace. Amen. May their souls and the souls of all the faithful departed, through the mercy of God, rest in peace. Amen.
In Latin
Requiem aeternam dona eis, Domine, et lux perpetua luceat eis. Requiescant in pace. Amen.
History
Drawn from the ancient Requiem liturgy — its opening words echo the Fourth Book of Esdras — this has been the Church's constant short prayer for the dead for over a millennium. It is the prayer Catholics reach for at gravesides, at the news of a death, and all through November, the month of the holy souls.
When to Pray
On hearing of any death, when passing a cemetery, on anniversaries of loss, and throughout November. It is the prayer to teach children so grief always has somewhere to go.