Pope John XXIII
Aeterna Dei Sapientia §48
The Magisterial Prerogative of St. Peter and His Successors
48 "And so if anything is rightly done and rightly decreed by Us, if anything is won from the mercy of God by Our daily supplications, it is due to his [Peter's] works and merits, whose power lives and whose authority prevails in his See." (42)
Source: Aeterna Dei Sapientia (Vatican.va)