John Chrysostom

And (Paul) said not to the sorcerer, "Wilt thou not cease to pervert" the proconsul? What may be the reason of John's going back from them? For "John," it says, "departing from them returned to Jerusalem": (he does it) because they are undertaking a still longer journey: and yet he was their attendant, and as for the danger, they incurred it (not he).-Again, when they were come to Perga, they hastily passed by the other cities, for they were in haste to the metropolis, Antioch.

Homily on Acts 28 ↗

Theophylact of Ohrid

John, called Mark, accompanied them in their evangelical journey from Palestine to Perga of Pamphylia. Then, when the apostles hastened their journey and with a firm, unyielding spirit began to arm themselves for labors, Mark, being a weak man who did not dare to undertake such a journey and those labors, dangers, and struggles that presented themselves in every city, fell behind the apostles and returned to Palestine — not denying Christ, but refusing to continue the journey, since it was difficult for him. …

Commentary on Acts ↗

Oecumenius

"John, having withdrawn." This is John, also called Mark, the cousin of Barnabas, who also wrote the Gospel according to Mark and was a disciple of Peter the chief, of whom he says in the Epistle: "Mark my son greets you." (1 Peter 5:13) Therefore this man, since the journey concerning Paul was to be prolonged, withdrew from them, although being a servant, because he would not undergo the dangers. [CHRYSOSTOM]

Commentary on Acts ↗

Cassiodorus

"Now when Paul and they that were with him had sailed from Paphos," etc. When Paul and Barnabas had sailed from Paphos with the rest who had come with them, they came to Perge in Pamphilia, and passed through it. John, departing from them at Perge, returned to Jerusalem. Paul and Barnabas, walking through Perge, came to Antioch in Pisidia. Entering the synagogue there, they listened to a reading of the prophets and the law. …

Complexiones on the Acts of the Apostles ↗