صَحِيحُ مُسْلِمٍ
Sahih Muslim 749 f
The Book of Prayer - Travellers
The night prayers are two by two, and Witr is one rakah at the end of the night
وَحَدَّثَنَا أَبُو كُرَيْبٍ، وَهَارُونُ بْنُ عَبْدِ اللَّهِ، قَالاَ حَدَّثَنَا أَبُو أُسَامَةَ، عَنِ الْوَلِيدِ بْنِ كَثِيرٍ، قَالَ حَدَّثَنِي عُبَيْدُ اللَّهِ بْنُ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ ابْنَ عُمَرَ، حَدَّثَهُمْ أَنَّ رَجُلاً نَادَى رَسُولَ اللَّهِ صلى الله عليه وسلم وَهُوَ فِي الْمَسْجِدِ فَقَالَ يَا رَسُولَ اللَّهِ كَيْفَ أُوتِرُ صَلاَةَ اللَّيْلِ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم مَنْ صَلَّى فَلْيُصَلِّ مَثْنَى مَثْنَى فَإِنْ أَحَسَّ أَنْ يُصْبِحَ سَجَدَ سَجْدَةً فَأَوْتَرَتْ لَهُ مَا صَلَّى . قَالَ أَبُو كُرَيْبٍ عُبَيْدُ اللَّهِ بْنُ عَبْدِ اللَّهِ . وَلَمْ يَقُلِ ابْنِ عُمَرَ .
Ibn 'Umar reported: A person called (the attention) of the Messenger of Allah (ﷺ) as he was in the mosque, and said: Messenger of Allah, how should I make the rak'ahs of the night prayer an odd number? Upon this the Messenger of Allah (ﷺ) said: He who prays (night prayer) he should observe it in pairs, but if he apprehends the rise of morning, he should observe one rak'ah; that would make the number odd (for the rak'ahs) observed by him. This was narrated by Abu Kuraib 'Ubaidullah b. 'Abdullah and Ibn 'Umar did not make mention of it.
Sahih Muslim, 749 fSahihصحيح