Mishkat al-Masabih 13 Marriage كتاب النكاح 204

وَعَنْ عَائِشَةَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «طَلَاقُ الْأَمَةِ تَطْلِيقَتَانِ وَعِدَّتُهَا حَيْضَتَانِ» . رَوَاهُ التِّرْمِذِيُّ وَأَبُو دَاوُدَ وَابْنُ مَاجَهْ وَالدَّارِمِيُّ

‘A’isha reported God’s Messenger as saying, “The divorce of a slave-woman consists in saying it twice, and her ‘idda period is two courses.” Tirmidhi, Abu Dawud, Ibn Majah and Darimi transmitted it.