Urwah bin al-Zubayr narrated from Marwan bin al-Hakam that he said: Ablution is required after touching the penis. Urwah rejected that. Marwan said: Busrah bint Safwan (may Allah be pleased with her) told me this. So he sent someone to Busrah, and she said: "The Messenger of Allah (peace and blessings be upon him) mentioned the things that require ablution, and he (peace and blessings be upon him) mentioned touching the penis."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20860