It is narrated from Hazrat Khawlah bint Hakim (may Allah be pleased with her) that she asked the Prophet (peace and blessings be upon him) about this issue: If a woman experiences in a dream the same condition that a man experiences, what is the ruling? The Prophet (peace and blessings be upon him) said: "There is no ghusl (ritual bath) upon her until there is emission, just as ghusl is not obligatory upon a man before emission."
Hadith Referenceمسند احمد / من مسند القبائل / 27312
Hadith Gradingحکم دارالسلام:حديث حسن، وهذا إسناد ضعيف لضعف على بن زيد، وقد توبع