Deus, qui hodiernam diem Apostolorum tuorum Petri et Pauli, martyrio consecrasti:  da Ecclesiae tuae, eorum in omnibus sequi praeceptum; per quos religionis sumpsit exordium.

O God, Who hast made this day holy by the martyrdom of Thine Apostles Peter and Paul:  grant that Thy Church may in all things follow the precepts of those through whom she received the beginnings of the Faith.

–From the Collect of the Mass