When is purity invalidated for those with continuous ritual discharge, such as the Mustahadah?
Chapter on Menstruation
Al-Mughni
Book of Purification
Primary text
The purity of these individuals is time-bound based on the instruction to perform Wudu for each prayer. If someone performs Wudu before the prayer time begins and discharge occurs, their purity is nullified because the entry into the prescribed time itself nullifies the purity performed outside that time, similar to how Tayammum is time-bound. Purity is also nullified if any other separate ritual impurity occurs.
Supporting text
If one performs Wudu after the time has entered, their purity is established, and subsequent unavoidable discharge does not nullify it. If one enters the prayer immediately after purification, or delays slightly for necessary matters like dressing or waiting for the congregation, or if they did not realize discharge occurred, the prayer is valid. If the prayer time elapses after discharge occurred, or another impurity occurs, the purity is voided. Imam Ahmad ruled that the permission to pray with that Wudu extends to performing supererogatory prayers and making up missed obligatory prayers until the next prayer time arrives, provided no other impurity occurs or the time expires.