Narrated Abdullah ibn Mas'ud:

The Messenger of Allah ﷺ led us in prayer in the time of danger. They (the people) stood in two rows. One row was behind the Messenger of Allah ﷺ and the other faced the enemy. The Messenger of Allah ﷺ led them in one rak'ah,and then the other section came and took their place; they went and faced the enemy. The Prophet ﷺ led them in one rak'ah and uttered the salutation. They stood up and prayed the second rak'ah by themselves and uttered the salutation and went away; they took the place of the other section facing the enemy. They came back and took their place. They prayed one rak'ah by themselves and then uttered the salutation.

حَدَّثَنَا عِمْرَانُ بْنُ مَيْسَرَةَ، حَدَّثَنَا ابْنُ فُضَيْلٍ، حَدَّثَنَا خُصَيْفٌ، عَنْ أَبِي عُبَيْدَةَ، عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ، قَالَ صَلَّى بِنَا رَسُولُ اللَّهِ ﷺ صَلاَةَ الْخَوْفِ فَقَامُوا صَفَّيْنِ صَفٌّ خَلْفَ رَسُولِ اللَّهِ ﷺ وَصَفٌّ مُسْتَقْبِلَ الْعَدُوِّ فَصَلَّى بِهِمْ رَسُولُ اللَّهِ ﷺ رَكْعَةً ثُمَّ جَاءَ الآخَرُونَ فَقَامُوا مَقَامَهُمْ وَاسْتَقْبَلَ هَؤُلاَءِ الْعَدُوَّ فَصَلَّى بِهِمُ النَّبِيُّ ﷺ رَكْعَةً ثُمَّ سَلَّمَ فَقَامَ هَؤُلاَءِ فَصَلَّوْا لأَنْفُسِهِمْ رَكْعَةً ثُمَّ سَلَّمُوا ثُمَّ ذَهَبُوا فَقَامُوا مَقَامَ أُولَئِكَ مُسْتَقْبِلِي الْعَدُوِّ وَرَجَعَ أُولَئِكَ إِلَى مَقَامِهِمْ فَصَلَّوْا لأَنْفُسِهِمْ رَكْعَةً ثُمَّ سَلَّمُوا .