Sahih Bukhari
Knowledge
Volume: 001 / Book Number: 003 / Hadith Number: 134
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).