John Wesley on 2 Samuel 8:1

And David took - Gath and her towns, as it is expressed in the parallel place, 1Chron 18:1. Which are called Metheg - ammah, or the bridle of Ammah, Gath was situate in the mountain of Ammah; and because this being the chief city of the Philistines, and having a king, which none of the rest had, was the bridle which had hitherto kept the Israelites in subjection.