The usual pattern is for a woman to menstruate for a quarter of the time—six or seven days. This is the pattern to which the Prophet, may Allah bless him and grant him peace, directed a woman experiencing non-menstrual bleeding who had neither an established cycle nor a way to distinguish menstrual from non-menstrual blood.

The scholars agree that there is no maximum duration for the interval of purity between two menstrual periods, since some women do not menstruate at all. If a woman has lengthy intervals between her menstrual periods, does she calculate her waiting period by one-third of a menstrual period, or is she treated like a woman whose condition is uncertain, menstruating for a year? The jurists hold two views on this.

Likewise, according to the correct view, there is no minimum duration for the interval of purity. A woman may have three menstrual periods in a month; even three periods in less time than that are possible. However, if she claims that her waiting period has ended within a duration contrary to the usual known pattern, members of her family familiar with her condition must testify on her behalf. This accords with what is reported from ʿAlī, may Allah be pleased with him, concerning a woman who claimed to have had three menstrual periods in one month.

The basic presumption is that everything discharged from the womb is menstruation unless evidence establishes that it is non-menstrual bleeding. Menstrual blood is the normal, natural blood released by the womb, whereas abnormal bleeding comes from a ruptured vein. The latter is like illness, whereas the presumption is health, not illness. Thus, whenever a woman sees blood flowing from her womb, it is menstruation, on account of which she refrains from prayer.

The view that she should take a ritual bath after one day and one night contradicts what is known from the Sunnah and the consensus of the early generations. We know that women menstruated during the Prophet’s lifetime, may Allah bless him and grant him peace, and every woman initially experiences menstruation for the first time. Yet despite this, the Prophet, may Allah bless him and grant him peace, did not instruct