Scientists differed on this matter. Some say the most days of menstruation are fifteen days, some say the most days are ten days, some say the most days menstruation are seventeen days, and as for the shortest days of menstruation, some say there is no limit to the days, and to that I say, the shortest menstrual period for us is one batch. Some say the least is a day and a night, and some say the least is three days. As for the shortest days of purification, some say ten days, some say eight days, some say fifteen, some say seventeen, and some say an hour, and I say that there is no limit to the most.