Hadith 10:204
‘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.
وَعَنْ عَائِشَةَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «طَلَاقُ الْأَمَةِ تَطْلِيقَتَانِ وَعِدَّتُهَا حَيْضَتَانِ» . رَوَاهُ التِّرْمِذِيُّ وَأَبُو دَاوُدَ وَابْنُ مَاجَهْ وَالدَّارِمِيُّ
Original Reference: Mishkat al-Masabih 3289