I say, and with God's success: Her waiting period ends after nineteen months except for three hours; because we need three menstrual cycles, each cycle lasting ten days, and three periods of purity, each period lasting six months except for one hour. Refer to: Al-Wiqayah and its explanation by Sadr al-Shari'ah, p. 128, and Fath Bab al-'Inayah 1: 141, among others, and God knows best.