Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says that the Messenger of Allah (peace and blessings be upon him) said: "The divorces of a slave woman are two, and her waiting period is two menstrual cycles."
Only Umar bin Shabib al-Musli narrated it in this marfu' form (attributed to the Prophet), and he was da'if (weak); the correct version is what Salim and Nafi' narrated from Ibn Umar as mawquf (his own statement), as has preceded.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرجعة / 15166