The Lord's prayer for the souls in purgatory, by Saint Mechtilde

Our Father, who art in Heaven…

I beg of Thee, loving Father, to pardon the souls in purgatory for not having worshiped Thee as they ought, but for having shut their hearts to Thee who did desire to dwell there.
To atone for their faults, I offer Thee the love and honor Thy cherished Son rendered Thee while on Earth and the abundant satisfaction by which He paid the debt of all their sins. Amen.

Hallowed be Thy Name…

I beg of Thee, O Loving Father, deign to pardon the souls in purgatory for not having worthily honored Thy Holy Name, for having seldom invoked it with devotion, for having often used it in vain and for having by their disgraceful lives rendered themselves unworthy of the name of Christian.
In satisfaction for their sins, I offer Thee the perfect holiness of Thy Son by which He exalted Thy Name when preaching and in all His Holy works. Amen.

Thy Kingdom come…

I beg of Thee, O Loving Father, to pardon the souls in purgatory for not having fervently desired nor carefully sought after Thy kingdom, in which alone true rest and eternal glory consist.
To expiate all indifference which they have shown for every sort of good, I offer Thee the holy desires by which Thy Son wished us to be the co-heirs of His kingdom. Amen.

Thy Will be done…

I beg of You, Gracious Father, to forgive the souls in purgatory, O loving Father, deign to pardon the souls in purgatory, and especially the souls of religious who during life preferred their will to Thine, for not having in all things loved Thy will, and for often living and acting according to their own.
To make reparation for their disobedience, I offer Thee the union of the Humble Heart of Thy Son with Thy Holy Will as also the ready obedience with which He obeyed Thee even unto the death of the Cross. Amen.

Give us this day our daily bread…

I beg of Thee, O loving Father, to pardon the souls in purgatory for not having received the most holy Sacrament of the Altar with the desire, the devotion, and love which It merits for having rendered themselves unworthy of It, or seldom or never having received It.
To expiate these sins, I offer Thee the perfect holiness and the devotion and love of Thy Son, as also the ardent love and ineffable desire which made Him give us the precious treasure. Amen.

And forgive us our trespasses as we forgive those who trespass against us…

I beg of Thee, O loving Father, to forgive the souls in purgatory the mortal sins into which they fell, especially in not forgiving those who offended Thee, and for not living their enemies. For these sins, I offer Thee the loving prayer Thy Son made upon the Cross for His enemies. Amen.

And lead us not into temptation…

I beg of Thee, O loving father to forgive the souls in purgatory for not having overcome their vices and concupiscences, for having consented to the temptations of the devil and the flesh, and for having willfully given way to bad actions.
To expiate these sins, I offer Thee the glorious victory by which Thy Son overcame the world and the devil, as also His most holy life with its works and fatigues, and His bitter Passion and Death. Amen.

But deliver us from evil…

and them, from every evil and every woe through the merits of Thy beloved Son, and bring us to the kingdom of Thy glory, which is none other than Thy most glorious Self. Amen