Sunan an-Nasa'i 1668
سنن النسائي#1668Sahihأَخْبَرَنَا عَمْرُو بْنُ عُثْمَانَ، وَمُحَمَّدُ بْنُ صَدَقَةَ، قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ حَرْبٍ، عَنِ الزُّبَيْدِيِّ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمٍ، عَنْ أَبِيهِ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " صَلاَةُ اللَّيْلِ مَثْنَى مَثْنَى فَإِذَا خِفْتَ الصُّبْحَ فَأَوْتِرْ بِوَاحِدَةٍ " .
It was narrated from Salim, from his father, that :The Prophet (ﷺ) said: "Prayers at night are two by two, then if you fear that dawn will come, pray witr with one rak'ah
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 - Agreed Upon
In-book reference: 20:71