Therefore disputed he - Or reasoned. He engaged in an argument with them.
With the devout persons - Those worshipping God after the manner of the Jews. They were Jewish proselytes, who had renounced idolatry, but who had not been fully admitted to the privileges of the Jews. See the notes on Acts 10:2.
And in the market - In the forum. It was not only the place where provisions were sold, but was also a place of great public concourse. In this place the philosophers were not infrequently found engaged in public discussion.