I say, and with God's success: The ten days from the beginning are menstruation, so it is permissible to end her menstruation with purity, not to begin it; because the purity that is considered like the continuous blood must occur between two bloods, thus it is necessary for the beginner to consider the first of them as menstruation by necessity. Refer to: Dhakhr al-Mutahilin and Manhal al-Waridin, pages 66-68, and God knows best.