We were in Medina, and when the muezzin called the adhan for the Maghrib prayer, the people would rush to the pillars and pray two rakats each. A stranger entering the mosque would think that the prayer had already been performed, because of the great number of people praying these two rakats.
كنا بالمدينة، فإذا أذن المؤذن لصلاة المغرب ابتدروا السواري، فيركعون ركعتين ركعتين، حتى إن الرجل الغريب ليدخل المسجد فيحسب أن الصلاة قد صليت من كثرة من يصليهما.
Bukhari narrated it in adhan (625), and Muslim in Travelers (837), both of them through two routes from Anas, and the wording given is Muslim's. In Bukhari's version, there was nothing between the adhan and the call to begin the prayer. Uthman bin Jabalah and Abu Dawud said, on the authority of Shubah, there was only a little between them.