John Chrysostom

"And we went before to ship, and sailed unto Thasos, there intending to take in Paul: for so had he appointed, minding himself to go afoot." We often find Paul parting from the disciples. For behold again, he himself goes afoot: giving them the easier way, and himself choosing the more painful. He went afoot, both that he might arrange many matters, and by way of training them to bear a parting from him.

Homily on Acts 43 ↗

Theophylact of Ohrid

He himself went on foot, giving them what was easier, while choosing for himself what was harder, and at the same time teaching them much and accustoming them to being separated from him.

Commentary on Acts ↗

Irenaeus

But that this Luke was inseparable from Paul, and his fellow-labourer in the Gospel, he himself clearly evinces, not as a matter of boasting, but as bound to do so by the truth itself. For he says that when Barnabas, and John who was called Mark, had parted company from Paul, and sailed to Cyprus, "we came to Troas;" and when Paul had beheld in a dream a man of Macedonia, saying, "Come into Macedonia, Paul, and help us," "immediately," he says, "we endeavoured to go into Macedonia, understanding that the Lord had called us to preach …

Against Heresies Book III, Chapter 14, Section 1 ↗