Sunan Abi Dawud 1416
سنن أبي داود#1416Sahihحَدَّثَنَا إِبْرَاهِيمُ بْنُ مُوسَى، أَخْبَرَنَا عِيسَى، عَنْ زَكَرِيَّا، عَنْ أَبِي إِسْحَاقَ، عَنْ عَاصِمٍ، عَنْ عَلِيٍّ، - رضى الله عنه - قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " يَا أَهْلَ الْقُرْآنِ أَوْتِرُوا فَإِنَّ اللَّهَ وِتْرٌ يُحِبُّ الْوِتْرَ " .
Narrated Ali ibn AbuTalib: The Prophet (ﷺ) said: Allah is single (witr) and loves what is single, so observe the witr, you who follow the Qur'an
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:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih Lighairihi
Zubair Ali ZaiDaif
In-book reference: 8:1