Sayyidah Busrah bint Safwan (may Allah be pleased with her), who was the maternal aunt of Marwan, said: I asked the Messenger of Allah (peace and blessings be upon him): O Messenger of Allah, is ablution required of one of us women when she touches her private parts? The Messenger of Allah (peace and blessings be upon him) said: "Whoever touches his private parts, among men and women, ablution is required of him."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20891