Musannaf Ibn Abi Shayba 1:1725

Ibn ‘Ulayyah narrated to us, from ‘Abd Allah ibn Abi Bakr, who said: I heard ‘Urwah ibn al-Zubayr narrating to my father. He said: Marwan mentioned to me the touching of the penis, so I said: "There is no ablution in it." He said: "But Busrah bint Safwan narrates regarding it." So he sent a messenger to her, and he mentioned that she narrated that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever touches his penis, let him perform ablution."