1Pet 5:13

“This also the presbyter [John] said: Mark, having become the interpreter of Peter, wrote down accurately, though not in order, whatsoever he remembered of the things said or done by Christ. For he neither heard the Lord nor followed him, but afterward, as I said, he followed Peter, who adapted his teaching to the needs of his hearers, but with no intention of giving a connected account of the Lord's discourses, so that Mark committed no error while he thus wrote some things as he remembered them. For he was careful of one thing, not to omit any of the things which he had heard, and not to state any of them falsely.”

“"Marcus, my son, salutes you." Mark, the follower of Peter, while Peter publicly preached the Gospel at Rome before some of Caesar's equites, and adduced many testimonies to Christ, in order that thereby they might be able to commit to memory what was spoken, of what was spoken by Peter, wrote entirely what is called the Gospel according to Mark. As Luke also may be recognised by the style, both to have composed the Acts of the Apostles, and to have translated Paul's Epistle to the Hebrews.”

“And thus when the divine word had made its home among them, the power of Simon was quenched and immediately destroyed, together with the man himself. And so greatly did the splendor of piety illumine the minds of Peter's hearers that they were not satisfied with hearing once only, and were not content with the unwritten teaching of the divine Gospel, but with all sorts of entreaties they besought Mark, a follower of Peter, and the one whose Gospel is extant, that he would leave them a written monument of the doctrine which had been orally communicated to them. Nor did they cease until they had prevailed with the man, and had thus become the occasion of the written Gospel which bears the name of Mark. And they say that Peter when he had learned, through a revelation of the Spirit, of that which had been done, was pleased with the zeal of the men, and that the work obtained the sanction of his authority for the purpose of being used in the churches. Clement in the eighth book of his Hypotyposes gives this account, and with him agrees the bishop of Hierapolis named Papias. And Peter makes mention of Mark in his first epistle which they say that he wrote in Rome itself, as is indicated by him, when he calls the city, by a figure, Babylon, as he does in the following words: "The church that is at Babylon, elected together with you, saluteth you; and so doth Marcus my son." [1 Peter 5:13]”

“The Church which is gathered in Babylon greets you, etc. He calls Rome Babylon figuratively, evidently because of the confusion of manifold idolatry. In the midst of which, the holy Church, now immature and very small, was shining forth, in the example of the Israelite people who once, small in number and captured, sitting by the rivers of Babylon, wept for the absence of the holy land, nor could they sing the Lord's song in a foreign land (Psalm 136). And blessed Peter appropriately, while exhorting his listeners to endure present adversities, mentions the Church which is established with him in Babylon, that is, in the confusion of tribulations. And yet, he confirms it to be gathered, to show that the holy city of God in this life cannot be free from the intermingling and oppression of the city of the devil, which Babylon signifies. He calls Mark his son, who is said to become his son through baptism. Hence it is clear that before he sent Mark from Rome to Alexandria to preach the gospel, he wrote this Epistle. In the time of Emperor Claudius, both Peter and Mark came to Rome, and Mark himself, after composing his Gospel in Rome, was sent to Alexandria. Whence it is inferred that when Peter sought a place and time to write this Epistle, the place was Rome, the time was during the reign of Claudius Caesar.”

“it was in the Roman dominions that the preaching of Christianity first became current in the days of the Apostles, and it was immediately afterwards extended to Persia by the Apostle Thaddaeus. And, to be sure we find this written in the Catholic Epistles: The Church that is in Babylon elect together with you, saluteth you”

“Peter calls Rome Babylon, because it was so remarkable and distinguished, as it had been for a long time in Babylon. Peter calls his son Mark according to the spirit, and not according to the flesh. To him, he entrusted the task of writing the Gospel. However, some have dared to assert that Mark was the son of the divine Peter according to the flesh, using as an argument what was said by Luke in the Acts of the Apostles. (Acts 12:1) For he says that Peter was miraculously brought out of prison by the angel of God, in which Herod had kept him, and after being released from the angelic conversation, Peter came to the house of the mother of John, who was surnamed Mark, as if he had come to his own house and to his lawful wife.”