Messenger of Allah ﷺ led the Fear-prayer with one of the two batches of the army while the other (batch) faced the enemy. Then the first batch went away and took places of their companions (i.e. second batch) and the second batch came and he led his second rakʿa with them. Then he (i.e. the Prophet: finished his prayer with Taslim and then each of the two batches got up and completed their remaining one rakʿa.  

أَنَّ رَسُولَ اللَّهِ ﷺ صَلَّى بِإِحْدَى الطَّائِفَتَيْنِ وَالطَّائِفَةُ الأُخْرَى مُوَاجِهَةُ الْعَدُوِّ ثُمَّ انْصَرَفُوا فَقَامُوا فِي مَقَامِ أَصْحَابِهِمْ فَجَاءَ أُولَئِكَ فَصَلَّى بِهِمْ رَكْعَةً ثُمَّ سَلَّمَ عَلَيْهِمْ ثُمَّ قَامَ هَؤُلاَءِ فَقَضَوْا رَكْعَتَهُمْ وَقَامَ هَؤُلاَءِ فَقَضَوْا رَكْعَتَهُمْ  

The Messenger of Allah (may peace he upon him) led on* of the two groups In one rak'ah of prayer in danger, while the other group faced the -enemy. Then they (the members of the first group) went back and replaced their companions who were facing the enemy. and then they (the members of the second group) came and the Messenger of Allah ﷺ led them in one rak'ah of prayer. Then the Messenger of Allah ﷺ pronounced salutation, and then they (the members of the Ant group) completed the rak'ah and they (the members of the second group) completed the rak'ah.  

صَلَّى رَسُولُ اللَّهِ ﷺ صَلاَةَ الْخَوْفِ بِإِحْدَى الطَّائِفَتَيْنِ رَكْعَةً وَالطَّائِفَةُ الأُخْرَى مُوَاجِهَةُ الْعَدُوِّ ثُمَّ انْصَرَفُوا وَقَامُوا فِي مَقَامِ أَصْحَابِهِمْ مُقْبِلِينَ عَلَى الْعَدُوِّ وَجَاءَ أُولَئِكَ ثُمَّ صَلَّى بِهِمُ النَّبِيُّ ﷺ رَكْعَةً ثُمَّ سَلَّمَ النَّبِيُّ ﷺ ثُمَّ قَضَى هَؤُلاَءِ رَكْعَةً وَهَؤُلاَءِ رَكْعَةً  

The Messenger of Allah ﷺ led one of the two groups in praying one rak'ah while the other group was facing the enemy, then they moved away and took the place of the others, and the others came and he led them in praying the other rak'ah, then he said the salam and they stood up and made up the other rak'ah, and the others stood up and made up the other rak'ah.  

أَنَّ رَسُولَ اللَّهِ ﷺ صَلَّى بِإِحْدَى الطَّائِفَتَيْنِ رَكْعَةً وَالطَّائِفَةُ الأُخْرَى مُوَاجِهَةُ الْعَدُوِّ ثُمَّ انْطَلَقُوا فَقَامُوا فِي مَقَامِ أُولَئِكَ وَجَاءَ أُولَئِكَ فَصَلَّى بِهِمْ رَكْعَةً أُخْرَى ثُمَّ سَلَّمَ عَلَيْهِمْ فَقَامَ هَؤُلاَءِ فَقَضُوا رَكْعَتَهُمْ وَقَامَ هَؤُلاَءِ فَقَضُوا رَكْعَتَهُمْ  

The Messenger of Allah ﷺ led one section in one rak'ah of prayer and the other section was facing the enemy. Then they turned away and took the position of the other section. They (the other section) came and he (the Prophet) led them in the second rak'ah. He then uttered the salutation. Thereafter they stood up and completed the remaining rak'ah, they went away and the other section completed their remaining rak'ah. Abu Dawud said: This tradition has been narrated by Nafi' and Khalid b. Ma'dan from Ibn 'Umar in like manner from the Prophet ﷺ. This has also been transmitted similarly by Masruq ad Yusuf b. Mihran on the authority of Ibn 'Abbas. This has been narrated by Yunus from al-Hasan from Abu Musa something similarly, saying that Abu Musa has done so.  

أَنَّ رَسُولَ اللَّهِ ﷺ صَلَّى بِإِحْدَى الطَّائِفَتَيْنِ رَكْعَةً وَالطَّائِفَةُ الأُخْرَى مُوَاجِهَةُ الْعَدُوِّ ثُمَّ انْصَرَفُوا فَقَامُوا فِي مَقَامِ أُولَئِكَ وَجَاءَ أُولَئِكَ فَصَلَّى بِهِمْ رَكْعَةً أُخْرَى ثُمَّ سَلَّمَ عَلَيْهِمْ ثُمَّ قَامَ هَؤُلاَءِ فَقَضَوْا رَكْعَتَهُمْ وَقَامَ هَؤُلاَءِ فَقَضَوْا رَكْعَتَهُمْ  

"The Prophet prayed Salat Al-Khawf, praying one Rak'ah with one of the two groups, while the other group was facing the enemy. (When the first group finished they first Rak'ah with him), they went and took position (of the second group, facing the enemy). Then the second group came and he led them in another Rak'ah, then he said the Taslim to them, while the group proceeded to complete their (second) Rak'ah. Thereafter, the first group stood up to finish their (second) Rak'ah."  

أَنَّ النَّبِيَّ ﷺ صَلَّى صَلاَةَ الْخَوْفِ بِإِحْدَى الطَّائِفَتَيْنِ رَكْعَةً وَالطَّائِفَةُ الأُخْرَى مُوَاجِهَةُ الْعَدُوِّ ثُمَّ انْصَرَفُوا فَقَامُوا فِي مَقَامِ أُولَئِكَ وَجَاءَ أُولَئِكَ فَصَلَّى بِهِمْ رَكْعَةً أُخْرَى ثُمَّ سَلَّمَ عَلَيْهِمْ فَقَامَ هَؤُلاَءِ فَقَضَوْا رَكْعَتَهُمْ وَقَامَ هَؤُلاَءِ فَقَضَوْا رَكْعَتَهُمْ  

The Messenger of Allah (may peace he upon him) led on* of the two groups In one rak'ah of prayer in danger, while the other group faced the -enemy. Then they (the members of the first group) went back and replaced their companions who were facing the enemy. and then they (the members of the second group) came and the Messenger of Allah ﷺ led them in one rak'ah of prayer. Then the Messenger of Allah ﷺ pronounced salutation, and then they (the members of the Ant group) completed the rak'ah and they (the members of the second group) completed the rak'ah. (Using translation from Muslim 839a)  

صَلَّى رَسُولُ اللهِ ﷺ صَلَاةَ الْخَوْفِ بِإِحْدَى الطَّائِفَتَيْنِ رَكْعَةً وَالطَّائِفَةُ الْأُخْرَى مُوَاجِهَةُ الْعَدُوِّ ثُمَّ انْصَرَفُوا وَقَامُوا فِي مَقَامِ أَصْحَابِهِمْ مُقْبِلِينَ عَلَى الْعَدُوِّ وَجَاءَ أُولَئِكَ فَصَلَّى بِهِمُ النَّبِيُّ ﷺ رَكْعَةً ثُمَّ سَلَّمَ ثُمَّ قَضَى هَؤُلَاءِ رَكْعَةً وَهَؤُلَاءِ رَكْعَةً  

The Messenger of Allah (may peace he upon him) led on* of the two groups In one rak'ah of prayer in danger, while the other group faced the -enemy. Then they (the members of the first group) went back and replaced their companions who were facing the enemy. and then they (the members of the second group) came and the Messenger of Allah ﷺ led them in one rak'ah of prayer. Then the Messenger of Allah ﷺ pronounced salutation, and then they (the members of the Ant group) completed the rak'ah and they (the members of the second group) completed the rak'ah. (Using translation from Muslim 839a)  

«صَلَّى رَسُولُ اللهِ ﷺ صَلَاةَ الْخَوْفِ بِإِحْدَى الطَّائِفَتَيْنِ رَكْعَةً وَالطَّائِفَةُ الْأُخْرَى مُوَاجِهَةُ الْعَدُوِّ ثُمَّ انْصَرَفُوا وَقَامُوا فِي مَقَامِ أَصْحَابِهِمْ مُقْبِلِينَ عَلَى الْعَدُوِّ وَجَاءَ أُولَئِكَ فَصَلَّى بِهِمُ النَّبِيُّ ﷺ رَكْعَةً ثُمَّ سَلَّمَ النَّبِيُّ ﷺ ثُمَّ قَضَى هَؤُلَاءِ رَكْعَةً وَهَؤُلَاءِ رَكْعَةً»  

The Messenger of Allah ﷺ led one section in one rak'ah of prayer and the other section was facing the enemy. Then they turned away and took the position of the other section. They (the other section) came and he (the Prophet) led them in the second rak'ah. He then uttered the salutation. Thereafter they stood up and completed the remaining rak'ah, they went away and the other section completed their remaining rak'ah. Abu Dawud said: This tradition has been narrated by Nafi' and Khalid b. Ma'dan from Ibn 'Umar in like manner from the Prophet ﷺ. This has also been transmitted similarly by Masruq ad Yusuf b. Mihran on the authority of Ibn 'Abbas. This has been narrated by Yunus from al-Hasan from Abu Musa something similarly, saying that Abu Musa has done so. (Using translation from Abū Dāʾūd 1243)   

أَنَّ رَسُولَ اللهِ ﷺ صَلَّى صَلَاةَ الْخَوْفِ بِإِحْدَى الطَّائِفَتَيْنِ رَكْعَةً وَالطَّائِفَةُ الْأُخْرَى مُوَاجِهَةٌ الْعَدُوَّ ثُمَّ انْصَرَفُوا فَقَامُوا فِي مَقَامِ أُولَئِكَ وَجَاءَ أُولَئِكَ فَصَلَّى بِهِمْ رَكْعَةً أُخْرَى ثُمَّ سَلَّمَ عَلَيْهِمْ ثُمَّ قَامَ هَؤُلَاءِ فَقَضَوْا رَكْعَتَهُمْ وَقَامَ هَؤُلَاءِ فَقَضَوْا رَكْعَتَهُمْ  

" عَنِ ابْنِ عُمَرَ قَالَ: صَلَّى النَّبِىُّ ﷺ صَلاَةَ الْخَوْف بِإِحْدَى الطَّائِفَتَيْنِ رَكعَةً، وَالطَّائِفَةُ الأُخْرَى مُوَاجِهَةٌ الْعَدُوَّ، ثُمَّ انْصَرَفُوا وَقَامُوا فِى مَقَامِ أصَحَابِهِمْ مُقْبلِينَ عَلَى الْعَدُوِّ، وَجَاءَ أُولَئِكَ فَصَلَّى بِهِمُ النَّبِىُّ ﷺ رَكعَةً، ثُمَّ سَلَّمَ النَّبِىُّ ﷺ ثُمَّ قَضَى هَؤُلاَءِ رَكعَةً وَهؤُلاَءِ رَكعَةً".