Imam Ahmad recorded that Abu Ayyash Az-Zuraqi radhiAllahu anhu said, “We were with the Messenger of Allah, sallAllahu aalyhi wa sallam, in the area of Usfan [a well-known place near Makkah], when the idolators met us under the command of Khalid bin Waleed, and they were between us and the Qiblah. The Messenger of Allah, sallAllahu aalyhi wa sallam, led us in Zuhr prayer, and the idolators said, ‘They were busy with something during which we had a chance to attack them’. They then said, ‘Next, there will come a prayer [Asr] that is dearer to them than their children and themselves’. However, Jibreel came down with these ayaat between the prayers of Zuhr and Asr
When the time for prayer came, the Messenger of Allah, sallAllahu aalyhi wa sallam commanded Muslims to hold their weapons and he made us stand in two lines behind him. When he bowed, we all bowed behind him. When he raised his head, we all raised our heads. The Prophet sallAllahu aalyhi wa sallam then prostrated with the line that was behind him while the rest stood in guard. When they finished with the prostration and stood up, the rest sat and performed prostration, while those who performed it stood up in guard after the two lines exchanged position. The Prophet sallAllahu aalyhi wa sallam then bowed and they all bowed after him, then raised their heads after he raised his head. Then the Prophet sallAllahu aalyhi wa sallam performed prostration with the line that was behind him, while the rest stood in guard. When those who made prostration sat, the rest prostrated. The Prophet sallAllahu aalyhi wa sallam then performed the tasleem and ended the prayer. The Messenger of Allah, sallAllahu aalyhi wa sallam, performed this prayer twice, once in Usfan and once in the land of Banu Sulaym.”
This is the narration recorded by Abu Dawud and an-Nasai.
Al-Bukhari recorded that ibn Abbas radhiAllahu anhu said, “Once the Prophet sallAllahu aalyhi wa sallam led the fear prayer and the people stood behind him. He said Allahu Akbar and the people said the same. He bowed and some of them bowed. Then he prostrated and they also prostrated. Then he stood for the second rakah and those who had prayed the first rakah left and guarded their brothers. The second party joined him and performed bowing and prostration with him. All the people were in prayer, but they were guarding one another during the prayer.”
Imam Ahmad recorded that Jabir bin Abdullah radhiAllahu anhu said that the Messenger of Allah, sallAllahu aalyhi wa sallam, led them in the fear prayer. A group of them stood before him and a group behind him. The Prophet sallAllahu aalyhi wa sallam led those who were behind him with one rakah and two prostrations. They then moved to the position of those who did not pray, while the others stood in their place, and the Messenger of Allah, sallAllahu aalyhi wa sallam, performed one rakah and two prostrations and then said the Salaam. Therefore, the Prophet sallAllahu aalyhi wa sallam prayed two rakah while they prayed one. An-Nasa’i recorded this Hadith, while Muslim collected other wordings for it.
Ibn Abi Hatim recorded that Salim said that his father said, وَإِذَا كُنتَ فِيهِمْ فَأَقَمْتَ لَهُمُ الصَّلَوةَ refers to the fear prayer. The Messenger of Allah, sallAllahu aalyhi wa sallam, led one group and prayed one rakah, while the second group faced the enemy. Then the second group that faced the enemy came and Allah’s Messenger sallAllahu aalyhi wa sallam led them, praying one rakah, and then said the Salaam. Each of the two groups then stood up and prayed one more rakah each (while the other group stood in guard).” The Group collected this Hadith with Ma`mar in its chain of narrators. This Hadith also has many other chains of narration from several Companions, and Al-Hafiz Abu Bakr Ibn Marduwyah collected these various narrations, as did Ibn Jarir.