Adam Clarke on Acts 21:39

I am a man which am a Jew - A periphrasis for, I am a Jew. See the note on Act 7:2.

Of Tarsus - no mean city - In the notes on Act 9:11, I have shown that Tarsus was a city of considerable importance, and in some measure a rival to Rome and Athens; and that, because of the services tendered to the Romans by the inhabitants, Julius Caesar endowed them with all the rights and privileges of Roman citizens. When St. Paul calls it no mean city, he speaks a language that was common to those who have had occasion to speak of Tarsus. Xenophon, Cyri Anabas. i., calls it, πολιν μεγαλην και ευδαιμονα, a great and flourishing city. Josephus, Ant. lib. i. cap. 6, sec. 6, says that it was παρ' αυτοις των πολεων ἡ αξιολογωτατη μητροπολις ουσα, the metropolis and most renowned city among them (the Cilicians.) And Ammianus Marcellinus, xiv. 8, says, Ciliciam Tarsus nobilitat, urbs perspicabilis: "Tarsus, a very respectable city; adorns Cilicia."