Sahih Bukhari

Narrated Zainab bint Um Salama:Um Sulaim said, ""O Allah's Messenger (ﷺ)! Verily Allah is not shy of (telling you) the truth. Is it essential for a woman to take a bath after she had a wet dream (nocturnal sexual discharge)?"" He said, ""Yes, if she notices discharge. On that Um Salama laughed and said, ""Does a woman get a (nocturnal sexual) discharge?"" He said, ""How then does (her) son resemble her (his mother)?