Sunan Ibn Majah, Volume 2, Book 5, Hadith 1175 (DarusSalam) ⓘ
Abu Mijlaz narrated that Ibn ‘Umar said: “The Messenger of Allah said: ‘Night prayers are to be offered two by two, and Witr is one Rak’ah.’ I said: ‘What do you think if I become drowsy and I want to sleep?’ He said: ‘Put “what do you think” up there with that star? (i.e., don’t think about it at all).’ I raised my head and saw As- Simak.* He repeated that the Messenger of Allah said, ‘Night prayers are to be offered two by two, and Witr is one Rak’ah, before dawn.’”
حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ الْمَلِكِ بْنِ أَبِي الشَّوَارِبِ، حَدَّثَنَا عَبْدُ الْوَاحِدِ بْنُ زِيَادٍ، حَدَّثَنَا عَاصِمٌ، عَنْ أَبِي مِجْلَزٍ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " صَلاَةُ اللَّيْلِ مَثْنَى مَثْنَى وَالْوِتْرُ رَكْعَةٌ " قُلْتُ أَرَأَيْتَ إِنْ غَلَبَتْنِي عَيْنِي أَرَأَيْتَ إِنْ نِمْتُ قَالَ اجْعَلْ أَرَأَيْتَ عِنْدَ ذَلِكَ النَّجْمِ . فَرَفَعْتُ رَأْسِي فَإِذَا السِّمَاكُ ثُمَّ أَعَادَ فَقَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " صَلاَةُ اللَّيْلِ مَثْنَى مَثْنَى وَالْوِتْرُ رَكْعَةٌ قَبْلَ الصُّبْحِ " .
also referenced under: Hadith 1175 (Reference) & Book 5, Hadith 1231 (In-Book)