Jami` at-Tirmidhi 454
جامع الترمذي#454Da'ifوَرَوَى سُفْيَانُ الثَّوْرِيُّ، وَغَيْرُهُ، عَنْ أَبِي إِسْحَاقَ، عَنْ عَاصِمِ بْنِ ضَمْرَةَ، عَنْ عَلِيٍّ، قَالَ الْوِتْرُ لَيْسَ بِحَتْمٍ كَهَيْئَةِ الصَّلاَةِ الْمَكْتُوبَةِ وَلَكِنْ سُنَّةٌ سَنَّهَا رَسُولُ اللَّهِ صلى الله عليه وسلم . حَدَّثَنَا بِذَلِكَ مُحَمَّدُ بْنُ بَشَّارٍ حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ مَهْدِيٍّ عَنْ سُفْيَانَ عَنْ أَبِي إِسْحَاقَ . وَهَذَا أَصَحُّ مِنْ حَدِيثِ أَبِي بَكْرِ بْنِ عَيَّاشٍ . وَقَدْ رَوَاهُ مَنْصُورُ بْنُ الْمُعْتَمِرِ عَنْ أَبِي إِسْحَاقَ نَحْوَ رِوَايَةِ أَبِي بَكْرِ بْنِ عَيَّاشٍ .
Sufyan Ath-Thawri and others reported from Abu Ishaq, from Asim bin Damrah, that :Ali said: "Al-Witr is not incumbent like the status of the obligatory prayers, but it is a Sunnah which Allah's Messenger practiced
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:
In-book reference: 3:3