Sunan an-Nasa'i 446
سنن النسائي#446SahihIt 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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih
In-book reference: 4:52