Urwah bin Zubair (may Allah have mercy on him) says that once Marwan discussed with me about "touching the private part." My opinion was that touching one's private part does not break wudu, while Marwan said that in this regard Hazrat Busrah bint Safwan (may Allah be pleased with her) narrated a hadith to him. Eventually, Marwan sent a messenger to Hazrat Busrah (may Allah be pleased with her). The messenger came back and reported that she had narrated this hadith: The Prophet (peace and blessings be upon him) said, "Whoever touches his private part should perform wudu."