Sunan An-Nasa'i
Hadith #446
It was narrated that Marwan bin Al-Hakam said that one should perform Wudu' after touching one's penis. Marwan said:""Busrah bint Safwan told me that."" 'Urwah sent someone to check that, and she said: ""The Messenger of Allah (ﷺ) mentioned what Wudu' is done for, and said: 'Touching the penis