Language:
كتاب الغسل
5  
Bathing (Ghusl)
(13)
Chapter: The washing away of emotional urethral discharge and performing ablution after it
(13)
باب غَسْلِ الْمَذْىِ وَالْوُضُوءِ مِنْهُ
Sahih al-Bukhari 269

Narrated `Ali:

I used to get emotional urethral discharge frequently. Being the son-in-law of the Prophet (ﷺ) I requested a man to ask him about it. So the man asked the Prophet (ﷺ) about it. The Prophet (ﷺ) replied, "Perform ablution after washing your organ (penis)."

حَدَّثَنَا أَبُو الْوَلِيدِ، قَالَ حَدَّثَنَا زَائِدَةُ، عَنْ أَبِي حَصِينٍ، عَنْ أَبِي عَبْدِ الرَّحْمَنِ، عَنْ عَلِيٍّ، قَالَ كُنْتُ رَجُلاً مَذَّاءً فَأَمَرْتُ رَجُلاً أَنْ يَسْأَلَ النَّبِيَّ صلى الله عليه وسلم لِمَكَانِ ابْنَتِهِ فَسَأَلَ فَقَالَ ‏ "‏ تَوَضَّأْ وَاغْسِلْ ذَكَرَكَ ‏"‏‏.‏
Reference : Sahih al-Bukhari 269
In-book reference : Book 5, Hadith 22
USC-MSA web (English) reference : Vol. 1, Book 5, Hadith 269
  (deprecated numbering scheme)