Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: A slave woman who is married to a slave and is then freed has the choice before her husband has intercourse with her. If her husband has had intercourse with her and she then claims ignorance, she will be suspected, her claim of ignorance will not be believed, and after intercourse she has no choice.
(b) In the narration of Ibn Jurayj from Ata bin Abi Rabah (may Allah have mercy on him): If the slave has had intercourse with the slave woman while she did not know, then she has the choice when she comes to know.
(c) Al-Hasan (may Allah have mercy on him) said: If, after the slave woman is freed, her slave husband has intercourse with her before she is given the choice, she is to be made to swear that she did not know, and then she is to be given the choice.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14287