حَدَّثَنَا مُحَمَّدُ بْنُ عُبَيْدٍ حَدَّثَنَا عُبَيْدُ اللَّهِ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ قَالَ سَأَلَ رَجُلٌ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَهُوَ عَلَى الْمِنْبَرِ عَنْ صَلَاةِ اللَّيْلِ قَالَ مَثْنَى مَثْنَى فَإِذَا خَشِيَ أَحَدُكُمْ أَنْ يُصْبِحَ صَلَّى وَاحِدَةً فَأَوْتَرَتْ لَهُ مَا صَلَّى
مسند امام احمد بن حنبل · Hadith 5793
It was narrated that Ibn 'Umar said: A man asked the Messenger of Allah (PBUH) when he was on the minbar, about prayer at night. He said: "It is two (rak'ahs) by two, then if one of you fears that dawn is about to break, let him pray one rak'ah (Witr), which will make what he has prayed odd-numbered."
Sanad
حَدَّثَنَا مُحَمَّدُ بْنُ عُبَيْدٍ حَدَّثَنَا عُبَيْدُ اللَّهِ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ