John Wesley on Matthew 6:5

The synagogues - These were properly the places where the people assembled for public prayer, and hearing the Scriptures read and expounded. They were in every city from the time of the Babylonish captivity, and had service in them thrice a day on three days in the week. In every synagogue was a council of grave and wise persons, over whom was a president, called the ruler of the synagogue. But the word here, as well as in many other texts, signifies any place of public concourse.