On the authority of a person who offered the prayer in time of danger along with the Messenger of Allah ﷺ at the battle of Dhat al-Riqa. One section of people stood in the row of prayer along with the Messenger of Allah ﷺ and the other section remained standing in front of the enemy. He led those who were with him in one rak'ah and remained standing (in his place) and they completed (the second rak'ah) by themselves. Then they turned away and arrayed before the enemy. Thereafter the other section came and he led them in the rak'ah which remained from his prayer. He then remained sitting (in his place) and they completed their one rak'ah by themselves. He then uttered the salutation along with them. Malik said: I like the tradition reported by Yazid b. Ruman (i.e. the present tradition) more than (other versions) I heard.  

عَنْ صَالِحِ بْنِ خَوَّاتٍ عَمَّنْ صَلَّى مَعَ رَسُولِ اللَّهِ ﷺ يَوْمَ ذَاتِ الرِّقَاعِ صَلاَةَ الْخَوْفِ أَنَّ طَائِفَةً صَفَّتْ مَعَهُ وَطَائِفَةً وِجَاهَ الْعَدُوِّ فَصَلَّى بِالَّتِي مَعَهُ رَكْعَةً ثُمَّ ثَبَتَ قَائِمًا وَأَتَمُّوا لأَنْفُسِهِمْ ثُمَّ انْصَرَفُوا وَصَفُّوا وِجَاهَ الْعَدُوِّ وَجَاءَتِ الطَّائِفَةُ الأُخْرَى فَصَلَّى بِهِمُ الرَّكْعَةَ الَّتِي بَقِيَتْ مِنْ صَلاَتِهِ ثُمَّ ثَبَتَ جَالِسًا وَأَتَمُّوا لأَنْفُسِهِمْ ثُمَّ سَلَّمَ بِهِمْ قَالَ مَالِكٌ وَحَدِيثُ يَزِيدَ بْنِ رُومَانَ أَحَبُّ مَا سَمِعْتُ إِلَىَّ  

The prayer time of danger should be offered in the following way: The imam should stand (for prayer) and a section of the people should stand along with him. The other section should stand facing the enemy. The imam should perform bowing and prostrate himself along with those who are with him. He then should stand (after prostration) and, when he stands straight, he should remain standing. They (the people) should (in the meantime) complete their remaining rak'ah (i.e. the second one). They they should utter the salutation, and turn away while the imam should remain standing. They should go before the enemy. Thereafter those who did not pray should come forward and utter the takbir (Allah is most great) behind imam. He should bow and prostrate along with them and utter the salutation. Then they should stand and completed their remaining rak'ah, and utter the salutation. Abu Dawud said: The tradition reported by Yahya b. Sa'id from al-Qasim is similar to the one transmitted by Yazid b. Ruman except that he differed with him in salutation. The tradition reported by 'Ubaid Allah is like the one reported by Yahya b. Sa'id, saying: He (the Prophet) remained standing.  

أَنْ يَقُومَ الإِمَامُ وَطَائِفَةٌ مِنْ أَصْحَابِهِ وَطَائِفَةٌ مُوَاجِهَةَ الْعَدُوِّ فَيَرْكَعُ الإِمَامُ رَكْعَةً وَيَسْجُدُ بِالَّذِينَ مَعَهُ ثُمَّ يَقُومُ فَإِذَا اسْتَوَى قَائِمًا ثَبَتَ قَائِمًا وَأَتَمُّوا لأَنْفُسِهِمُ الرَّكْعَةَ الْبَاقِيَةَ ثُمَّ سَلَّمُوا وَانْصَرَفُوا وَالإِمَامُ قَائِمٌ فَكَانُوا وِجَاهَ الْعَدُوِّ ثُمَّ يُقْبِلُ الآخَرُونَ الَّذِينَ لَمْ يُصَلُّوا فَيُكَبِّرُونَ وَرَاءَ الإِمَامِ فَيَرْكَعُ بِهِمْ وَيَسْجُدُ بِهِمْ ثُمَّ يُسَلِّمُ فَيَقُومُونَ فَيَرْكَعُونَ لأَنْفُسِهِمُ الرَّكْعَةَ الْبَاقِيَةَ ثُمَّ يُسَلِّمُونَ