Sahih al-Bukhari, Book 5, Hadith 22 (In-Book) ⓘ

Narrated `Ali: I used to get emotional urethral discharge frequently. Being the son-in-law of the Prophet I requested a man to ask him about it. So the man asked the Prophet about it. The Prophet 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 ‏" ‏‏.‏