Sahih Al Bukhari (282)

عن أم سلمة قالت: جاءت أم سليم إلى رسول الله صلى الله عليه وسلم فقالت: يا رسول الله، إن الله لا يستحيي من الحق، فهل على المرأة من غسل إذا احتلمت؟ قال النبي صلى الله عليه وسلم: (إذا رأت الماء). فغطت أم سلمة، تعني وجهها، وقالت: يا رسول الله، وتحتلم المرأة؟ قال: (نعم، تربت يمينك، فيم يشبهها ولدها ( .

Um Salamah (may Allah be pleased with her) narrated: Um Sulaym came to Allah's Messenger (peace be upon him) and said: "Verily, Allah is not shy of (telling you) the truth. Is it necessary for a woman to take a bath after she has a wet dream (nocturnal sexual discharge?) The Prophet (peace be upon him) replied: "Yes, if she notices a discharge." Um Salamah, then covered her face and asked: "O Allah's Messenger! Does a woman get a discharge?" He replied: "Yes, let your right hand be in dust (An Arabic expression you say to a person when you contradict his statement meaning "you will not achieve goodness"), and that is why the son resembles his mother."