O Messenger of Allah, verily, Allah does not feel shy of the truth. If a woman had a wet dream, would it be obligatory on her to take a ritual bath? He replied: Yes, if she sees vaginal fluid
Authentic hadithعن أم سلمة رضي الله عنها قالت: «جاءت أمُّ سُلَيمٍ امرأةُ أَبِي طَلحة إلى رسول الله صلى الله عليه وسلم فقالت: يا رسول الله، إنَّ الله لا يَسْتَحيِي من الحَقِّ، فهل على المرأة من غُسْلٍ إِذَا هِيَ احْتَلَمَت؟ فقال رسول الله صلى الله عليه وسلم : نعم، إِذَا رَأَت المَاء».
Umm Salamah (may Allah be pleased with her) reported: Umm Sulaym, the wife of Abu Talhah, came to the Messenger of Allah (may Allah's peace and blessings be upon him) and said: "O Messenger of Allah, verily, Allah does not feel shy of the truth. If a woman had a wet dream, would it be obligatory on her to take a ritual bath?" He replied: "Yes, if she sees vaginal fluid."
Explanation
Umm Sulaym al-Ansāriyyah (may Allah be pleased with her) went to the Prophet (may Allah's peace and blessings be upon him) to ask him about something. But as her question pertained to the private parts, something people would usually feel shy to talk about, she said a few words as a prelude to the question, preparing the attendees for what was to come. She noted that Allah, the Almighty, does not refrain from speaking the true things which people may refrain from due to shyness, as long as mention of such things is useful. After this introduction, she got to the point and asked: Is a woman required to take a ritual bath if she sees in a dream that she engages in sexual intercourse. In reply, the Prophet (may Allah's peace and blessings be upon him) said: Yes, she is, if she sees vaginal fluid.
Source · Narrated by Bukhari & Muslim
From the Hadith Encyclopedia (hadeethenc.com).