When it is said
The Gelasian Sacramentary puts it in its third book, the prayers for Sundays, as the opening prayer of a Mass.
Later Roman books give it to the 12th Sunday after Pentecost.
The English Prayer Book of 1549 made it the collect, the prayer of the day, for the 12th Sunday after Trinity.
Where it comes from
No author known
The Gelasian Sacramentary
The Gelasian Sacramentary is named after Gelasius, bishop of Rome from AD 492 to 496. A sacramentary held the prayers of the Mass, both the fixed ones and those that changed from day to day. This one’s oldest copy was written in the 600s or early 700s for a church in the land of the Franks. It is now in the Vatican Library.
H. A. Wilson, The Gelasian Sacramentary (1894); William Bright, Ancient Collects (1864), the preface and appendix
The prayer’s first form?
In 1864 the scholar William Bright pointed to a shorter prayer in the Leonine Sacramentary, another book of Roman Mass prayers. He thought it was probably this prayer’s first form. It speaks to the “God of heavenly powers, Who givest more than we ask or deserve”. Then it asks that His mercy give us what we could never claim on our own merits.
William Bright, Ancient Collects (1864), page 132; Charles Lett Feltoe, Sacramentarium Leonianum (1896)
The Scripture in it
Now to Him Who is able to do immeasurably more than all we ask or imagine, according to His power that is at work within us …
Bible text: Berean Standard Bible, public domain.
In Latin
Omnipotens sempiterne Deus,
qui abundantia pietatis tuae
et merita supplicum excedis et vota,
effunde super nos misericordiam tuam,
ut dimittas quae conscientia metuit,
et adiicias quod oratio non praesumit.
Per.
From the Gelasian Sacramentary, as H. A. Wilson printed it in 1894.