It was narrated that Sayyar bin al-Ma'roor said: I heard 'Umar giving a khutbah, and he said: The Messenger of Allah (ﷺ) built this mosque and we, the Muhajireen and Ansar, were with him. If it gets too crowded, then let one of you prostrate on his brother's back. And he saw people (on one occasion) praying in the street and said: Pray in the mosque,