This thou knowest, that all they which are in Asia,.... Either those that followed the apostle from Asia to Rome; or who came from thence thither, upon business, and were upon the spot when the apostle was in his greatest troubles, and yet all forsook him and no man stood by him; or else the churches and ministers in Asia, that is, a great number of them; for it cannot be said of every minister and church, and of all the members of churches there, what follows,be turned away from me; were ashamed of him, because of his chain, and despised him under his afflictions, and had him in abhorrence and contempt, and revolted from his doctrine; though the defection was very general, and the apostle appeals to Timothy for the truth of it, as a fact well known to him: "this thou knowest"; Timothy being at Ephesus, which was in Asia; and since there was so great an apostasy in the country where he was, the above exhortations were very seasonable, to hold fast the form of sound words, and keep the good thing committed to him; seeing so many were falling off from the truth of the Gospel:of whom are Phygellus and Hermogenes: who very likely were ministers of the word, and who had shone for a while, but were now stars fallen from heaven, had erred from the faith, and were become apostates, and proved men of corrupt minds, and deceivers of the people; and it may be that these were more open and infamous than some others, or might be more known to Timothy, and therefore are particularly mentioned.
They are both of them said to have been of the seventy disciples; See Gill on "Lu 10:1" and afterwards followers of Simon Magus. The name of the first of these signifies a "fugitive", and such was he from the cause of Christ.
Pliny makes mention of a town in Asia, called Phygella, from the fugitives which built it; and the latter signifies born of Mercury; there was one of the name in Tertullian's time, against whom he wrote.
Nat. Hist. l. 5. c.