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

that he said concerning the fear prayer: "The Imam should stand facing the Qiblah, and a group of them should stand with him, and another group should stand in the direction of the enemy, facing towards the row (of worshippers). He should lead them in one Rakah, then they should bow and do two prostrations by themselves where they are. Then they should go and take the place of the others, and the others should come and pray one Rakah, bowing and prostrating with the leader. Then he will have prayed two Rakah and they will have prayed one; then they should perform another Rakah, bowing and performing two prostrations." Daif