Must a woman whose menstruation continues for 15 days, and who experiences a two-day period of cleanness after three days from the start of her cycle, perform ghusl and pray immediately upon seeing the cleanness, or should she wait until the bleeding completely stops after 15 days?

The maximum duration for menstruation is fifteen days. All days during which blood is observed are considered menstruation, as long as this period is not exceeded. As for the period of purity that interrupts the days of bleeding, there is a disagreement among scholars. Some consider it a valid period of purity, and the woman must perform ghusl (definition) (ritual bath) and pray upon seeing it. If the blood returns, she reverts to the state of menstruation, provided that the total number of bleeding days and the interspersed days of purity do not exceed fifteen days.