ENOfficial
‘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.
Source: sunnah.com
Other translations
Arabic
وَعَنْ عَائِشَةَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «طَلَاقُ الْأَمَةِ تَطْلِيقَتَانِ وَعِدَّتُهَا حَيْضَتَانِ» . رَوَاهُ التِّرْمِذِيُّ وَأَبُو دَاوُدَ وَابْنُ مَاجَهْ وَالدَّارِمِيُّ
sunnah.com