Jamieson, Fausset and Brown on Acts 18:19

19. he came to Ephesus--the capital of the Roman province of Asia. (See Introduction to Ephesians). It was a sail, right across from the west to the east side of the Ægean Sea, of some eight or ten days, with a fair wind.

left them there--Aquila and Priscilla.

but he himself entered into the synagogue--merely taking advantage of the vessel putting in there.

and reasoned with the Jews--the tense here not being the usual one denoting continuous action (as in Ac 17:2; 18:4), but that expressing a transient act. He had been forbidden to preach the word in Asia (Ac 16:6), but he would not consider that as precluding this passing exercise of his ministry when Providence brought him to its capital; nor did it follow that the prohibition was still in force.