Qasim bin Muhammad used to say that Yazid bin Abdul Malik created a separation between men and those women who were umm walad, and whose masters had died, and who had married after one or two menstrual cycles. And he ordered them to observe an 'iddah of four months and ten days. Then Qasim bin Muhammad said: Subhan Allah, Allah Almighty says in His Book: "Those among you who die and leave behind wives, they should observe an 'iddah of four months and ten days." And umm walad are not included among wives.