The narrator said: I heard Urwah say: Marwan sent a messenger to Busrah (may Allah be pleased with her) and asked her about this hadith, and she reported that the Messenger of Allah (peace and blessings be upon him) said: "When one of you touches his private organ, let him perform ablution."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20873