This prayer invokes God's mercy upon souls in purgatory who most honored his divine love during life.
As we all strive to reach the gates of Heaven, sometimes our past sins prevent us from reaching full communion with God upon our death. This doesn’t meant that we didn’t love God during life, but that we struggled to stay on the road of perfection.
Here is a prayer from the Raccolta that invokes God’s mercy upon those souls in purgatory who loved God during life and are drawing closes to his embrace in Heaven.
O Lord God Almighty, I pray Thee by the Precious Body and Blood of Thy Divine Son Jesus, which He gave with His own Hand upon the eve of His Passion to His beloved apostles to be their meat and drink, and which He left to His whole Church to be a perpetual sacrifice and the life-giving food of His own faithful people, deliver the souls in purgatory, and especially that one which was most devoted to this Mystery of infinite love, that it may with the same Thy Divine Son, and with The Holy Spirit, ever praise Thee for Thy love therein in eternal glory. Amen.