Sunan an-Nasa'i 436
سنن النسائي#436Sahihأَخْبَرَنَا مُحَمَّدُ بْنُ حَاتِمٍ قَالَ: حَدَّثَنَا عَبِيدَةُ قَالَ: حَدَّثَنَا سُلَيْمَانُ الأَعْمَشُ عَنْ حَبِيبِ بْنِ أَبِي ثَابِتٍ عَنْ سَعِيدِ بْنِ جُبَيْرٍ عَنِ ابْنِ عَبَّاسٍ عَنْ عَلِيٍّ رَضِيَ اللَّهُ عَنْهُ قَالَ: كُنْتُ رَجُلاً مَذَّاءً فَأَمَرْتُ رَجُلاً فَسَأَلَ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَقَالَ: «فِيهِ الْوُضُوءُ»
It was narrated that 'Ali, may Allah be please with him, said:"I was a man who emotted a great deal of Madhi. I told a man to ask the Prophet (ﷺ) (about that) and he said: 'Wudu' (is required) for that
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: 4:42