Salim bin 'Abdullah bin 'Umar reported: The Messenger of Allah ( صلی اللہ علیہ وسلم ) (may peace he upon him) led one of the two groups In one rak'ah of prayer in danger, while the other group faced the enemy. Then they (the members of the first group) went back and replaced their companions who were facing the enemy. And then they (the members of the second group) came and the Apostle of Allah ( صلی اللہ علیہ وسلم ) led them in one rak'ah of prayer. Then the Apostle of Allah ( صلی اللہ علیہ وسلم ) pronounced salutation, and then they (the members of the Ant group) completed the rak'ah and they (the members of the second group) completed the rak'ah.