Acts 19:8

εἰσελθὼν δὲ εἰς τήν συναγωγήν, and having entered into the synagogue. As the incident of John’s disciples is mentioned before anything else, it seems likely that St Paul found them among the few Christian brethren in Ephesus, and began his teaching of them before he commenced his visits to the synagogue.

ἐπὶ μῆνας τρεῖς, for three months. Going there, that is, on all occasions of religious service, and so giving to his brethren of Israel a full opportunity of hearing all his reasoning, and of inquiring whether what he taught was in accordance with the Scriptures. The abiding a longer time with them, which they had asked for (Acts 18:20) on his previous visit, does not seem to have gained him more adherents among the Jews. Perhaps he had noticed when the request was made that it was not with great fervour. Otherwise, it is not like the Apostle to pass by an opened door.

διαλεγόμενος, reasoning. The word is the same as in Acts 17:2. There ἀπὸ τῶν γραφῶν is added. The same sense is no doubt intended here. It must be from their Scriptures that the congregation of the synagogue would be convinced.