Musnad Ahmad 1249:4

Abdullah said: I found in my father’s book, in his own handwriting: Abu al-Yaman narrated to us, he said: Shu’ayb informed us, from al-Zuhri, who said: Abdullah ibn Abi Bakr ibn Hazm al-Ansari informed me that he heard Urwah ibn al-Zubayr saying: Marwan mentioned during his governorship of Medina that one must perform ablution (wudu) after touching the penis if a man reaches it with his hand. I denied that to him and said: "There is no ablution for one who touches it." Marwan said: "Busrah bint Safwan informed me that she heard the Messenger of Allah (peace and blessings of Allah be upon him) mentioning what requires ablution, and the Messenger of Allah (peace and blessings of Allah be upon him) said: 'And one performs ablution from touching the penis.'" Urwah said: I did not cease arguing with Marwan until he called a man from his guards and sent him to Busrah to ask her about what she had narrated regarding that. Busrah sent back to him the same as what Marwan had narrated to me from her.