Sunan an-Nasa'i 136
سنن النسائي#136Sahihأَخْبَرَنَا أَبُو دَاوُدَ، سُلَيْمَانُ بْنُ سَيْفٍ قَالَ حَدَّثَنَا أَبُو عَتَّابٍ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ أَبِي إِسْحَاقَ، عَنْ أَبِي حَيَّةَ، قَالَ رَأَيْتُ عَلِيًّا - رضى الله عنه - تَوَضَّأَ ثَلاَثًا ثَلاَثًا ثُمَّ قَامَ فَشَرِبَ فَضْلَ وَضُوئِهِ وَقَالَ صَنَعَ رَسُولُ اللَّهِ صلى الله عليه وسلم كَمَا صَنَعْتُ .
It was narrated that Abu Hayyah said:"I saw 'Ali performing Wudu', washing each part thrice. Then he stood up and drank the water that was left over from his Wudu' and said: 'The Messenger of Allah (ﷺ) did as I have done
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: 1:137