Hasan al-Basri, Ibrahim al-Nakha'i, and al-Sha'bi (may Allah have mercy on them) said: If a slave woman is divorced and she has not yet begun menstruating, then she should observe her waiting period by months. If she menstruates before the months are completed, then she should start her waiting period from the menstruation. If menstruation occurs after the months are completed, then her waiting period is already complete.