Sayyiduna Bara’ bin ‘Azib (may Allah be pleased with him) narrated that we used to pray behind the Prophet (peace and blessings of Allah be upon him). When he would say“Sami‘ Allahu liman hamidah”(i.e., when he would raise his head from bowing), none of us would bend his back (for prostration) until he (the Prophet) had placed his forehead on the ground.