Urwah bin al-Zubayr related that he and Marwan discussed the issue of ablution after touching the private part. 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) command ablution after touching the private part. It was as if Urwah did not give his words any weight, so Marwan sent a guard to her. He came back and informed them that she had heard the Messenger of Allah (peace and blessings be upon him) command ablution after touching the private part.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20855