The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day
20/34. Chapter:
How many (rak'ahs) is witr?
Sunan an-Nasai
أَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا يَحْيَى، وَمُحَمَّدٌ، قَالاَ حَدَّثَنَا ثُمَّ، ذَكَرَ كَلِمَةً مَعْنَاهَا شُعْبَةُ عَنْ قَتَادَةَ، عَنْ أَبِي مِجْلَزٍ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " الْوَتْرُ رَكْعَةٌ مِنْ آخِرِ اللَّيْلِ " .
It was narrated from Ibn Umar that: The Prophet (ﷺ) said: "Witr is one rak'ah at the end of the night."
Reference : Sunan an-Nasa'i 1690In-book reference : Book 20, Hadith 93English translation : Vol. 2, Book 20, Hadith 1691