Sunan an-Nasa'i 153
سنن النسائي#153Sahihأَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ أَخْبَرَنَا جَرِيرٌ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَلِيٍّ، - رضى الله عنه - قَالَ قُلْتُ لِلْمِقْدَادِ إِذَا بَنَى الرَّجُلُ بِأَهْلِهِ فَأَمْذَى وَلَمْ يُجَامِعْ فَسَلِ النَّبِيَّ صلى الله عليه وسلم عَنْ ذَلِكَ فَإِنِّي أَسْتَحِي أَنْ أَسْأَلَهُ عَنْ ذَلِكَ وَابْنَتُهُ تَحْتِي . فَسَأَلَهُ فَقَالَ " يَغْسِلُ مَذَاكِيرَهُ وَيَتَوَضَّأُ وُضُوءَهُ لِلصَّلاَةِ " .
It was narrated that 'Ali said:"I said to Al-Miqdad: 'If a man is intimate with his wife and excretes prostatic fluid but does not have intercourse - ask the Prophet (ﷺ) about that, for I am too shy to ask him about it since his daughter is married to me.' So he asked him, and he said: 'Let him wash his male member and perform Wudu' as for Salah
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: 1:154