Sunan Ibn Majah
602
Hasan+2

It was narrated from Khawlah bint Hakim that:She asked the Messenger of Allah about a woman who sees in her dream that which a man sees. He said: "She does not have to take a bath unless she has an orgasm, just as man does not have to take a bath unless he has an orgasm

HasanAl-Albani
HasanMuhammad Fouad Abd al-Baqi