It is narrated from Abu Hurairah, may Allah be pleased with him, that the Messenger of Allah, peace and blessings be upon him, camped between Dajnan and Usfan. The polytheists said: The Muslims love the Asr prayer even more than their forefathers and children. Make full preparations; we must launch a sudden attack on them. Meanwhile, Jibreel (Gabriel), peace be upon him, came and instructed the Prophet, peace and blessings be upon him, to divide his companions into two groups: lead one group in prayer while the other group stands behind them holding their protective gear and weapons; then let the second group pray with the Prophet, peace and blessings be upon him, while the first group takes up their protective gear and weapons. In this way, each group will perform one rak‘ah with the Messenger of Allah, peace and blessings be upon him, and the Prophet, peace and blessings be upon him, will complete two rak‘ahs.
Hadith Referenceالفتح الربانی / أبواب صلاة الخوف وهى أنواع / 2959
Benefit: … It is possible that this hadith is describing the same incident that has already been mentioned in the narration of Sayyiduna Abu Ayyash Zurqi radi Allahu anhu. If this is accepted, then the followers (muqtadis) would also perform two rak‘ahs each. In any case, from other ahadith, the evidence for only one rak‘ah has also been established.