A.T. Robertson Commentary 3 John 1:7

"because that for the sake of the Name they went forth, taking nothing of the Gentiles." — 3 John 1:7 (ASV)

For the sake of the Name (υπερ του ονοματος). The name of Jesus. See Ac 5:4; Romans 1:5 for υπερ του ονοματος and Jas 2:7 for the absolute use of "the name" as in 1 Peter 4:16. "This name is in essence the sum of the Christian creed" (Westcott) as in 1 Corinthians 12:3; Romans 10:9. It is like the absolute use of "the Way" (Acts 9:2; 19:9,23; Acts 24:22).

Taking nothing (μηδεν λαμβανοντες). Present active participle with the usual negative with participles (1 John 2:4).

Of the Gentiles (απο των εθνικων). Instead of the usual εθνων (Luke 2:32), late adjective for what is peculiar to a people (εθνος) and then for the people themselves (Polybius, Diodorus, not in LXX), in N.T. only here, Matthew 5:47; 6:7; 18:17. Like our heathen, pagan. John is anxious that Christian missionaries receive nothing from the heathen, as our missionaries have to watch against the charge of being after money. There were many travelling lecturers out for money. Paul in 1Colossians 9 defends the right of preachers to pay, but refuses himself to accept it from Corinth because it would be misunderstood (cf. 1 Thessalonians 2:6ff.; 2 Corinthians 12:16ff. 12:16ff.). Note απο here as in collecting taxes (Matthew 17:25) rather than παρα, which may be suggestive.