Sunan an-Nasa'i, Book 1, Hadith 196 (In-Book) ⓘ
It was narrated from Anas that Umm Sulaim asked the Messenger of Allah about a woman who sees in her dream something like a man sees. He said: "If water is released then let her perform Ghusl."
أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا عَبْدَةُ، قَالَ حَدَّثَنَا سَعِيدٌ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، أَنَّ أُمَّ سُلَيْمٍ، سَأَلَتْ رَسُولَ اللَّهِ صلى الله عليه وسلم عَنِ الْمَرْأَةِ تَرَى فِي مَنَامِهَا مَا يَرَى الرَّجُلُ قَالَ " إِذَا أَنْزَلَتِ الْمَاءَ فَلْتَغْتَسِلْ " .
also referenced under: Volume 1, Book 1, Hadith 195 (DarusSalam)