John Chrysostom

"Receive him therefore in the Lord with all joy." "In the Lord" either means spiritually and with much zeal, or rather "in the Lord" means God willing. Receive him in a manner worthy of saints, as saints should be received with all joy. All this he does for their sakes, not for that of his messengers, for greater gain has the doer than the receiver of a good deed. "And such hold in honor," that is, receive him in a manner worthy of saints.

Homily on Philippians 9 ↗

Theophylact of Ohrid

That is, receive him graciously, in a manner pleasing to God, or as befits saints. Paul says this for the benefit of the Philippians themselves, because the one who does good receives more benefit than the one who receives it. "Hold such people in honor." Lest it should seem that he favors Epaphroditus alone, he exhorts them to honor all in general who display the same virtue.

Commentary on Philippians ↗

Thomas Aquinas

Then he concludes by indicating how he should be received and why. He should be received honorably in the Lord, whose minister he is: "You received me as an angel of God, as Christ Jesus" (Gal. 4:14); "Let the elders who rule well be considered worthy of double honor, especially those who labor in preaching and teaching" (1 Tim. 5:17).

Commentary on Philippians ↗