Sahih al-Bukhari, Hadith 132 ⓘ
Narrated `Ali: I used to get the emotional urethral discharge frequently so I requested Al-Miqdad to ask the Prophet about it. Al-Miqdad asked him and he replied, "One has to perform ablution (after it)." (See Hadith No. 269).
حَدَّثَنَا مُسَدَّدٌ، قَالَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ دَاوُدَ، عَنِ الأَعْمَشِ، عَنْ مُنْذِرٍ الثَّوْرِيِّ، عَنْ مُحَمَّدٍ ابْنِ الْحَنَفِيَّةِ، عَنْ عَلِيٍّ، قَالَ كُنْتُ رَجُلاً مَذَّاءً فَأَمَرْتُ الْمِقْدَادَ أَنْ يَسْأَلَ النَّبِيَّ صلى الله عليه وسلم فَسَأَلَهُ فَقَالَ " فِيهِ الْوُضُوءُ " .
also referenced under: Book 3, Hadith 74 (In-Book) & Volume 1, Book 3, Hadith 134 (USC-MSA)