It was narrated from Salih bin Khawwat, from Sahl bin Abi Hathmah that:

The Messenger of Allah (ﷺ) led them in offering the fear prayer. Some formed a row behind him and some formed a row facing the enemy. He led them in praying one rak'ah, then they moved away and the others came, and he led them in praying one rak'ah, then they got up and each (group) made up the other rak'ah.

أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَحْيَى، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ الْقَاسِمِ، عَنْ أَبِيهِ، عَنْ صَالِحِ بْنِ خَوَّاتٍ، عَنْ سَهْلِ بْنِ أَبِي حَثْمَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم صَلَّى بِهِمْ صَلاَةَ الْخَوْفِ فَصَفَّ صَفًّا خَلْفَهُ وَصَفًّا مُصَافُّو الْعَدُوِّ فَصَلَّى بِهِمْ رَكْعَةً ثُمَّ ذَهَبَ هَؤُلاَءِ وَجَاءَ أُولَئِكَ فَصَلَّى بِهِمْ رَكْعَةً ثُمَّ قَامُوا فَقَضَوْا رَكْعَةً رَكْعَةً ‏.‏