Q: Might you know the provenance of the formula “May the Passion of our Lord Jesus Christ” (93 in the sacrament of penance)?
==
A: I treated your question in my book on the Order of Penance, Be Renewed. The revisers traced that formula to the 15th century Penitential of Vallicella II. But Thomas Aquinas had already recommended the second part of it, so its origins are quite old.
It was the 5th element of the 5-part preconciliar absolution.