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.  

أَنَّ رَسُولَ اللَّهِ ﷺ 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  

[Machine] The Messenger of Allahﷺ performed the prayer of fear, with those behind him forming a row, and another row equivalent to the enemy. He prayed with them one unit of prayer, then these (those who were behind him) went to the position of these (those equivalent to the enemy), and these (those equivalent to the enemy) came (forward), and he prayed with them one unit of prayer, then he said the tasleem. So it was two units for the Prophetﷺ and one unit for each group.  

صَلَّى رَسُولُ اللهِ ﷺ صَلَاةَ الْخَوْفِ بِذِي قَرَدٍ صَفًّا خَلْفَهُ وَصَفًّا مُوَازِيَ الْعَدُوِّ وَصَلَّى بِهِمْ رَكْعَةً ثُمَّ ذَهَبَ هَؤُلَاءِ إِلَى مَصَافِّ هَؤُلَاءِ وَجَاءَ هَؤُلَاءِ فَصَلَّى بِهِمْ رَكْعَةً ثُمَّ سَلَّمَ فَكَانَتْ لِلنَّبِيِّ ﷺ رَكْعَتَيْنِ وَلِكُلِّ طَائِفَةٍ رَكْعَةً  

[Machine] "We were with the Messenger of Allah ﷺ , so he arranged the rows behind him and they were in prayer. He said the takbeer and they all said the takbeer together, then he prayed with the row behind him and another row parallel to the enemy. He said, 'Then these people went and those people came, so he prayed a rak'ah with them. Then those who prayed with him in the first rak'ah stood up and completed their place. Then these people went to the rows of those people and those people came and completed a rak'ah."  

كُنَّا مَعَ رَسُولِ اللهِ ﷺ فَصَفَّ صَفَّا خَلْفَهُ وَصَفٌّ مُوَازِي الْعَدُوِّ قَالَ وَهُمْ فِي صَلَاةٍ كُلُّهُمْ قَالَ وَكَبَّرَ وَكَبَّرُوا جَمِيعًا فَصَلَّى بِالصَّفِّ الَّذِي يَلِيهِ رَكْعَةً وَصَفٌّ مُوَازِي الْعَدُوِّ قَالَ ثُمَّ ذَهَبَ هَؤُلَاءِ وَجَاءَ هَؤُلَاءِ فَصَلَّى بِهِمْ رَكْعَةً ثُمَّ قَامَ هَؤُلَاءِ الَّذِينَ صَلَّى بِهِمُ الرَّكْعَةَ الثَّانِيَةَ فَقَضَوْا مَكَانَهُمْ ثُمَّ ذَهَبَ هَؤُلَاءِ إِلَى مَصَافِّ هَؤُلَاءِ وَجَاءَ أُولَئِكَ فَقَضَوْا رَكْعَةً  

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. (Using translation from Nasāʾī 1536)  

أَنَّ رَسُولَ اللهِ ﷺ «صَلَّى بِهِمْ صَلَاةَ الْخَوْفِ فَصَفَّ صَفًّا خَلْفَهُ وَصَفًّا مُصَافِّي الْعَدُوِّ فَصَلَّى بِهِمْ رَكْعَةً ثُمَّ ذَهَبَ هَؤُلَاءِ وَجَاءَ أُولَئِكَ فَصَلَّى بِهِمْ رَكْعَةً ثُمَّ قَامُوا فَقَضَوْا رَكْعَةً رَكْعَةً»  

[Machine] The Messenger of Allah ﷺ performed the prayer of fear, so he arranged the rows behind him and the rows parallel to the enemy. He prayed with them one unit of prayer, then these people went to the place of those people, and those people came to the place of these people, so he prayed with them one unit of prayer, then he gave the salaam.  

صَلَّى رَسُولُ اللهِ ﷺ صَلَاةَ الْخَوْفِ فَصَفَّ صَفًّا خَلْفَهُ وَصَفًّا مُوَازِي الْعَدُوِّ فَصَلَّى بِهِمْ رَكْعَةً ثُمَّ ذَهَبَ هَؤُلَاءِ إِلَى مَصَافِّ هَؤُلَاءِ وَجَاءَ هَؤُلَاءِ إِلَى مَصَافِّ هَؤُلَاءِ فَصَلَّى بِهِمْ رَكْعَةً ثُمَّ سَلَّمَ  

"عَنْ سَهْلِ بْنِ أَبِى حَثْمَةَ قَالَ: يَقُومُ الإِمَامُ فِى صَلاَةِ الْخَوْفِ، وَيَقَومُ صَفٌّ خَلْفَهُ، وَصَفٌّ مُوَازِى الْعَدُوِّ، فَيُصَلِّى بِهَؤُلاَءِ رَكْعَةً، فَإِذَا صَلَّى بهِمْ رَكْعَةً قَامُوا مَكَانَهُمْ وَالإِمَامُ قَائِمٌ، فَقَضَوْا رَكعَةً، ثُمَّ ذَهَبُوا إِلَى مَصَافِّ أُولَئِكَ، وَجَاءَ أُوَلَئِكَ فَصَلَّى بِهِمْ رَكعَةً، ثُمَّ قَامُوا مَكَانَهُمْ فَقَضَوْا رَكْعَةً".