THOSE WHO EARNESTLY HELP THE HOLY SOULS MAY WELL HOPE TO AVOID PURGATORY
The Holy Souls whom we relieve or release by our Masses and good works pray for us with such indescribable fervour that God cannot refuse to hear their prayers. One of the principal graces they ask for their friends is that these shall have little or no Purgatory. No one knows better than they the awful intensity of the Purgatorial flames; no one, therefore, can pray for us as they do. Let us remember that:
a) God thanks as done to Himself what we do to others. When we relieve or release any of the Holy Souls, we relieve or release, as it were, God Himself. How ready, therefore, will He not be to hear the prayers offered by these souls for us.
b) Our Blessed Lord lays down clearly the great law: "By that measure by which you measure, it will be measured to you again" In proportion, consequently, to our generosity towards the Holy Souls will God's mercy and generosity be towards us. Those who work heart and soul for the relief of the Holy Souls may thus well hope that their Purgatory will be entirely remitted, or notably lessened. On the other hand, those who neglect the Holy Souls may justly fear a severe judgment and a long Purgatory.
~ Excerpt from How to Avoid Purgatory by Fr. Paul O'Sullivan ~