O Lord God Almighty, I beseech Thee by the Precious Body and Blood of Thy divine Son Jesus, which He Himself on the night before His Passion gave as meat and drink to His beloved Apostles and bequeathed to His Holy Church to be the perpetual Sacrifice and life-giving nourishment of His faithful people, deliver the souls in purgatory, but most of all, that soul which was most devoted to this Mystery of infinite love, in order that it may praise Thee therefore, together with Thy Divine Son and the Holy Spirit in Thy glory for ever. Amen.
Further reading
This prayer entrusts the departed to God through the gift of Christ’s Body and Blood. In Our Faithful Departed, Leonard J. DeLorenzo explores remembrance, prayer for the dead and the communion we share in Christ, including the place of the Eucharist in that continuing bond.
Our Faithful Departed: Where They Are and Why It Matters by Leonard J. DeLorenzo (paperback) on Amazon (paid link)