Chapter on Menstruation, Istihada (abnormal bleeding), and Nifas (postpartum bleeding)

Muhammad ibn Al-Hasan commented: “The meaning of "ten days" refers to extending up to ten days, and expressions with numerical attributes can substitute one another. We have already explained that precautionary waiting (istizhar) is usually for one, two, or three days. However, if it reaches ten days, that is the maximum duration of menstruation, and there is no precautionary extension beyond that.”