John Trapp on Mark 8:29-30

Verse 29. Thou art the Christ] This was much in few. Here is not Thou art Peter, and upon this Rock, &c. Which if either Saint Mark or Saint Peter had esteemed (as Papists now do) the foundation of the Christian Church, it had not been here omitted (as Beza well observeth) sith it goes for currant among the Ancients, that Saint Mark wrote this Gospel at Saint Peters mouth.