What is the ruling concerning the required frequency of ablution for a woman experiencing Istihada?

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The woman experiencing Istihada is commanded to perform ablution for every prescribed prayer. She may then use that single ablution to perform both the obligatory missed prayers (Qada') and supererogatory prayers until the time for the next prescribed prayer arrives. This ruling stems directly from the Prophet's command to her, which contained no detailed stipulations regarding the cessation of blood, making detailed stipulations contrary to the explicit report. Considering the intricacies of cessation would impose undue hardship (haraj), contrary to the principle established in the Quran (Quran 22:78), and no such detail was transmitted from the Prophet or the Companions.