I learned of the prayer of St. Gertrude while enjoying the
Full of Grace, Women and the Abundant Life study series
by Johnnette S. Benkovic.
She detailed the promise of God for one who prays this prayer.
God promised that many souls would enter Heaven from Purgatory
when prayerfully offered.
We chose it to be on the back of Matthias' funeral card
and pray it as a family with our petitions every week at his grave.