What is the ruling on the cessation of istihadah (non-menstrual vaginal bleeding) or yellowish discharge before the onset of the next menstrual period, and what is the required duration of purity between the cessation of istihadah and the onset of menstruation for all the blood within the possible period to be considered menstruation and for the ruling on the mustahadah (woman experiencing istihadah) to be abandoned?

Determining the days of menstruation for a woman experiencing irregular bleeding (istihada) depends on three situations:

1. The Woman with a Regular Period (al-Mu'tādah): She has a known monthly cycle. Her menstruation is considered to be for the duration of her usual days, and she abstains from prayer thereafter.

2. The Discerning Woman (al-Mumayyiza): She does not have a fixed cycle, but she can distinguish between menstrual blood (dark, thick, and odorous) and irregular bleeding. Her menstruation is what possesses the characteristics of menstrual blood, and anything else is irregular bleeding.

3. The Woman Lacking a Regular Period and Discretion (Fāqidat al-'Ādah wa al-Tamyīz): She has neither a regular cycle nor the ability to distinguish. She follows the common practice of the women of her family, or the general practice of women (six or seven days).

As for the beginner whose bleeding has continued: If the bleeding covers the entire month, or most of it, she is considered to be experiencing irregular bleeding (mustahada). Determining the end of menstruation and the beginning of irregular bleeding for a beginner is primarily by distinguishing the blood. If this is not possible, then by referring to the custom of her female relatives. Otherwise, it is by referring to the common custom of women (six or seven days).