Sunan Ibn Majah, Chapter: The Chapters of Establishing the Prayer and the Sunnah Regarding Them

that the Prophet (saw) led his Companions in the fear prayer. He led them all in bowing, then the Messenger of Allah (saw) and the row nearest him prostrated, and the others stood up, then when he stood up, they prostrated twice by themselves. Then the front row moved back and took their place, and they moved forward until they formed the front row. Then the Prophet (saw) led them all in bowing, then the Messenger of Allah (saw) and the row nearest to him prostrated, and when they raised their heads, the others prostrated twice. So all of them bowed with the Prophet (saw) and some of them prostrated by themselves, and the enemy was in the direction of the Qiblah. Hasan