On the Certainty of S. Peter

O God, Who didst bestow upon Thy blessed Apostle Peter the keys to the kingdom of heaven, and didst appoint unto him the high priesthood for binding and loosing: vouchsafe, that by the help of his intercession we may be delivered from the bonds of our iniquities; Who livest and reignest with Thee, in the unity of the Holy Ghost, ever one God, world without end. Amen.