Urwah bin al-Zubayr said: Marwan mentioned that ablution is to be performed after touching the penis when a man reaches it with his hand. I rejected that and said: There is no ablution upon one who touches it. Marwan said: Busrah bint Safwan (may Allah be pleased with her) told me that she heard the Messenger of Allah (peace and blessings be upon him) mentioning the things that require ablution, and the Messenger of Allah (peace and blessings be upon him) said: "And ablution is to be performed after touching the penis." Urwah said: I kept arguing with Marwan about this until he called a man from his guards and sent him to Busrah to ask her about what she had narrated concerning it. Busrah sent him the same as what Marwan had told me from her.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20863