You have also, by your very admonition, brought together the planting that was made by Peter and Paul at Rome and at Corinth; for both of them alike planted in our Corinth and taught us; and both alike, teaching similarly in Italy, suffered martyrdom at the same time.
Letter to Soter of Rome [inter A.D. 166 -174] as recorded by Eusebius
"But as it would be a very long task, to enumerate in such a volume as this, the successions of all the churches : pointing out that tradition which the greatest, and most ancient, and universally known Church, — founded and constituted, at Rome, by the two most glorious Apostles, Peter and Paul, — derives from the Apostles, and that faith announced to all men, which, through the succession of (her) bishops, has come down to us, we confound all those who, in any way, whether through pleasing themselves, or vain-glory, or blindness, and perverse opinion, assemble otherwise as suit them.
For with this Church, on account of its superior origin, it is necessary that every church agree, that is, all the faithful of the whole world everywhere maintain that tradition which is from Apostles."
Against Heresies 3:3:2 [A.D. 189]
Matthew also issued among the Hebrews a written Gospel in their own language, while Peter and Paul were evangelizing in Rome and laying the foundation of the Church. After their departure, Mark, the disciple and interpreter of Peter, also handed down to us in writing what had been preached by Peter.
Against Heresies 3:1:1 [A.D. 189]
Let us see what milk the Corinthians drained from Paul; against what standard the Galatians were measured for correction; what the Philippians, Thessalonians, and Ephesians read; what even the nearby Romans sound forth, to whom both Peter and Paul bequeathed the Gospel and even sealed it with their blood.
Against Marcion 4:5:1 [inter A.D. 207-212]