It is narrated from several Companions (may Allah be pleased with them) that the Prophet (peace and blessings be upon him) said: When a slave woman is granted her freedom, she is given the choice, provided that her husband has not had intercourse with her; if she wishes, she may separate from her husband. But if he has had intercourse with her, then she no longer has this choice and cannot separate from him.
Hadith Referenceمسند احمد / مسند المدنيين رضي الله عنهم اجمعين / 16620
Hadith Gradingحکم دارالسلام:حديث حسن، سماع الحسن بن موسي من ابن لهيعة بعد احتراق كتبه ، وقد توبع