Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrated that the Prophet Muhammad (peace and blessings be upon him) led a group in (fear) prayer, while another group stood facing the enemy. Then, after this group had completed their prayer and moved to take the place of their companions, the second group came and the Prophet (peace and blessings be upon him) led them in one rak'ah of prayer. After that, he concluded the prayer with them by saying salam. Then this group stood up and completed their remaining rak'ah, and the first group also stood up and completed their remaining rak'ah.