Sunan an-Nasa'i 1689
سنن النسائي#1689Sahihأَخْبَرَنَا مُحَمَّدُ بْنُ يَحْيَى بْنِ عَبْدِ اللَّهِ، قَالَ حَدَّثَنَا وَهْبُ بْنُ جَرِيرٍ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ أَبِي التَّيَّاحِ، عَنْ أَبِي مِجْلَزٍ، عَنِ ابْنِ عُمَرَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " الْوَتْرُ رَكْعَةٌ مِنْ آخِرِ اللَّيْلِ " .
It was narrated fom Ibn Umar that:The Prophet (ﷺ) said: "Witr is one rak'ah at the end of the night
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih Muslim
In-book reference: 20:92