The jurists of the people of Madinah whose opinion is authoritative used to say: When a slave woman is married to a slave and they are both freed together, the woman has no choice. And if the slave woman was freed first and remained silent until her husband was freed as well, then she has no choice either.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14273