SACERDOS ab Ordinario delegatus, rite confessus, aut saltem corde peccata sua detestans, peracto, si commode fieri possit, Sanctissimo Missæ sacrificio, divinoque auxilio piis precibus implorato, superpelliceo et stola violacea indutus
The priest delegated by the Ordinary to perform this office should first go to confession or at least elicit an act of contrition, and, if convenient, offer the holy Sacrifice of the Mass, and implore God's help in other fervent prayers. He vests in surplice and purple stole.
Remarks about the translation
This is the beginning of the "Rite for Exorcism" according to the Roman Ritual of the Roman Catholic Church.