When it is said
In the Old Gelasian book it opens the Mass for the third Sunday after Easter week.
The Book of Common Prayer kept it as the collect for the Fourth Sunday after Easter.
Where it comes from
No author known
From an old Roman service book
The Gelasian Sacramentary is a book of prayers for the Mass of the Church of Rome. It is the second oldest Western service book to survive. Its one surviving copy was made in Gaul about AD 750, from a Roman core put together between about AD 628 and 715.
The Cult of Saints, University of Oxford, E07005: the Gelasian Sacramentary; H. A. Wilson, The Gelasian Sacramentary (1894), p. 103
Into the Prayer Book
The English Book of Common Prayer took this prayer from the Latin as its collect for the Fourth Sunday after Easter. The Oxford scholar William Bright traced the Prayer Book’s collects to their sources. In 1864 he listed this one among those that come from the Gelasian book.
William Bright, Ancient Collects, 3rd edition (1864), appendix; The Book of Common Prayer (1662), the Fourth Sunday after Easter
The Scripture in it
For where your treasure is, there your heart will be also.
Bible text: Berean Standard Bible, public domain.
In Latin
Deus, qui fidelium mentes unius efficis voluntatis,
da populis tuis, id amare quod praecipis, id desiderare quod promittis,
ut inter mundanas varietates ibi nostra fixa sint corda ubi vera sunt gaudia.
Per.
From the Gelasian Sacramentary, ed. H. A. Wilson (Oxford, 1894), page 103, on archive.org.