What are the signs of the cessation of menstruation, and what is the ruling concerning my previous prayers and fasting if I used to perform ghusl immediately upon the cessation of blood without waiting for the white discharge, knowing that yellow discharges would continue, that my mother used to issue fatwas to me concerning that, and that waiting for the white discharge might prolong the duration of menstruation?

A woman knows she has become pure by one of two signs: dryness (a clean cotton swab), or the white discharge (a white fluid that appears after menstruation). Any yellowish discharge connected to menstruation is considered part of the menses, so a woman should not perform ghusl (ritual purification bath) upon seeing it. As for the actions that have already passed, you may act upon the opinion of those who do not consider yellowish discharge to be menstruation at all. While this is a less preferred opinion, some scholars permit it after the event has occurred and it is difficult to rectify the situation.