It was narrated from Marwan bin Al-Hakam that:
He asked Abu Hurairah: Did you offer the fear prayer with the Messenger of Allah (ﷺ)? Abu Hurairah said: Yes. He asked: When? He said: In the year of the campaign to Najd. The Messenger of Allah (ﷺ) stood up to pray 'Asr and a group stood with him, and another group as facing the enemy, with their backs toward the Qiblah. The Messenger of Allah (ﷺ) said the takbir, and they all said the takbir, those who were with him and those who were with him facing the enemy. Then the Messenger of Allah (ﷺ) bowed once and the group that was with him bowed, then he and the group that was with him prostrated twice, while the others were standing facing the enemy. Then the Messenger of Allah (ﷺ) stood up and the group that was with him stood and went to face the enemy, and the group that had been facing the enemy came and bowed and prostrated while the Messenger of Allah (ﷺ) was standing there. Then they stood up, and the Messenger of Allah (ﷺ) bowed again, and they bowed and prostrated with him. Then the group that had been facing the enemy came and bowed and prostrated, while the Messenger of Allah (ﷺ) and those who were with him were sitting. Then the Messenger of Allah (ﷺ) said the taslim and they all said the taslim. So the Messenger of Allah (ﷺ) had prayed two rak'ahs and each of the two groups had prayed two rak'ahs.