Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: Sayyidah Umm Sulaym (may Allah be pleased with her), who was the mother of Sayyiduna Anas bin Malik (may Allah be pleased with him), asked the Prophet (peace and blessings be upon him). She said: "O Messenger of Allah, what if a woman also sees what a man sees (that is, if a woman has a wet dream, what is the ruling)?" The Prophet (peace and blessings be upon him) said: "When a woman sees that and has a discharge, she should take a ritual bath (ghusl)."
Ahmad recorded it; its chain contains Abd al-Jabbar bin Umar al-Ayli, whom Yahya bin Ma'in and others declared "da'if" (weak), while Muhammad bin Sa'd declared him "thiqah" (trustworthy); the remaining narrators of this report are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1449