Zaynab bint Abi Salamah · The Book of Purification

It was narrated from Umm Salamah that the Messenger of Allah (ﷺ) at (meat from) a shoulder, then Bilal came to him and he went out to pray, and he did not touch water.

"O Messenger of Allah, Allah is not shy to tell the truth. Does a women have to perform Ghusl if she has a wet dream?" He said: "Yes, if she sees water." Umm Salamah laughed and said: "Do women really have wet dreams?" The Messenger of Allah (ﷺ) said: "How else would her child resemble her?" That is, if she has an emission of the fluid of an orgasm.

"The Messenger of Allah (ﷺ) and I would sleep under a single blanket when I was menstruating. If anything got on him from me, he would wash that spot and no more, and pray in it, then come back. If anything got on it again from me, he would do likewise and no more, and he would pray in it."