John Chrysostom

It seems to me, this Philip was one of the seven; for from Jerusalem he would not have gone southwards, but to the north; but from Samaria it was towards the south. "The same is desert:" so that there is no fear of an attack from the Jews. And he did not ask, Wherefore? but arose and went.

Homily on Acts 19 ↗

Theophylact of Ohrid

It seems to me that this Philip was one of the seven, because otherwise from Jerusalem he would have gone not to the south, but to the north, whereas from Samaria, where Philip who belonged to the number of the seven was staying and teaching, the road goes to the south. "To the road that goes from Jerusalem to Gaza, to the one which is desert." The Angel said this so that Philip would not fear an attack from the Jews.

Commentary on Acts ↗

Oecumenius

"Go toward the south." He would not have been going from Jerusalem toward the south, but toward the north; but from Samaria, where Philip of the seven was residing and teaching then, the road is toward the south.

Commentary on Acts ↗

Bede

To the way that goes down from Jerusalem to Gaza, this is desert. Not the road, but Gaza is called desert. For that old Gaza, which was once the boundary of the Canaanites near Egypt, was utterly destroyed, and another in its place was built elsewhere. This allegorically represents the people of the Gentiles, formerly deserted by the worship of God, nor cultivated by the preaching of any prophets. …

Commentary on Acts ↗

Cassiodorus

"Now an angel of the Lord spoke to Philip, saying," etc. An angel told Philip to go to the way where queen Candace's eunuch was about to pass. The eunuch, returning from Jerusalem, where he had come to adore on account of the devotion of his mind, was sitting in his chariot, reading the passage in the prophet Isaiah where he says: "He was led as a sheep to the slaughter; and as a lamb before his shearer, he did not open his mouth", etc. …

Complexiones on the Acts of the Apostles ↗