Sunan an-Nasa'i, Volume 2, Book 18, Hadith 1530 (DarusSalam) ⓘ

It was narrated that Tha'labah bin Zahdam said: "We were with Sa'eed bin Al-'Asi in Tabaristan, and Hudhaifah bin Al-Yaman was with us. He said: 'Which of you offered the fear prayer with the Messenger of Allah?' Hudhaifah said: 'I did', and he described it. He said: 'The Messenger of Allah offered the fear prayer, leading one group who had formed rows behind him in praying one rak'ah, while the other group was between him and the enemy. So he led the group that was near him in praying one rak'ah, then they left and took the place of others, and the others came and he led them in praying one rak'ah.'"

أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا وَكِيعٌ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنِ الأَشْعَثِ بْنِ أَبِي الشَّعْثَاءِ، عَنِ الأَسْوَدِ بْنِ هِلاَلٍ، عَنْ ثَعْلَبَةَ بْنِ زَهْدَمٍ، قَالَ كُنَّا مَعَ سَعِيدِ بْنِ الْعَاصِي بِطَبَرِسْتَانَ وَمَعَنَا حُذَيْفَةُ بْنُ الْيَمَانِ فَقَالَ أَيُّكُمْ صَلَّى مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم صَلاَةَ الْخَوْفِ فَقَالَ حُذَيْفَةُ أَنَا فَوَصَفَ فَقَالَ صَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم صَلاَةَ الْخَوْفِ بِطَائِفَةٍ رَكْعَةً صَفٍّ خَلْفَهُ وَطَائِفَةٍ أُخْرَى بَيْنَهُ وَبَيْنَ الْعَدُوِّ فَصَلَّى بِالطَّائِفَةِ الَّتِي تَلِيهِ رَكْعَةً ثُمَّ نَكَصَ هَؤُلاَءِ إِلَى مَصَافِّ أُولَئِكَ وَجَاءَ أُولَئِكَ فَصَلَّى بِهِمْ رَكْعَةً ‏.‏