Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says: "A slave (husband) can give two divorces to a free (wife), and the waiting period (‘iddah) for the woman will be three menstrual cycles. A free (husband) can give two divorces to a slave wife, and the waiting period for that woman will be the waiting period of a slave woman, that is, two menstrual cycles."