بُلُوغُ الْمَرَامِ
Bulugh al-Maram 1114
Marriage
وَعَنِ اِبْنِ عُمَرَ رَضِيَ اَللَّهُ عَنْهُمَا قَالَ: { طَلَاقُ اَلْأَمَةِ تَطْلِيقَتَانِ, وَعِدَّتُهَا حَيْضَتَانِ } رَوَاهُ اَلدَّارَقُطْنِيُّ [1] .
Narrated Ibn 'Umar (RA): The divorce of a slave-woman occurs by saying it (the divorce word) twice, and her 'Iddah (waiting period) is two menses. [Reported by ad-Daraqutni].
Sunnah.com reference: Book 8, Hadith 177