Musannaf Ibn Abi Shayba 10:1064

Abu Bakr narrated to us, he said: Abd al-Rahman ibn Mahdi narrated to us, from Hammad ibn Zayd, from Ali ibn al-Hakam, from al-Dahhak, regarding the slave woman: If she is divorced twice, then she is manumitted during her waiting period, he said: She observes a waiting period of two menstrual cycles. And if she is divorced once, then she is manumitted during her waiting period, he said: She observes a waiting period of three menstrual cycles, and her husband has more right to her.