acts 16:13 And on the sabbath we went out of the city by a river side, where prayer was wont to be made; and we sat down, and spake unto the women which resorted thither. - Free Bible Online

      13. on the sabbath day--the first after their arrival, as the words imply.
      we went out of the city--rather, as the true reading is, "outside of the (city) gate."
      by a river-side--one of the small streams which gave name to the place ere the city was founded by Philip of Macedon.
      where prayer was wont to be made--or a prayer-meeting held. It is plain there was no synagogue at Philippi (contrast Ac 17:1), the number of the Jews being small. The meeting appears to have consisted wholly of women, and these not all Jewish. The neighborhood of streams was preferred, on account of the ceremonial washings used on such occasions.
      we sat down and spake unto the women, &c.--a humble congregation, and simple manner of preaching. But here and thus were gathered the first-fruits of Europe unto Christ, and they were of the female sex, of whose accession and services honorable mention will again and again be made.

JFB.