Please note: this fatwa has been translated by artificial intelligence.
Question
A woman who does not become pure from menstruation for more than ten days, how does she calculate the days if she menstruated in the afternoon and wanted to fast on the day she becomes pure in the afternoon? Is it permissible for her to intend to fast before her purification wash in the afternoon on the same day?
Answer
I say, and with God's help: It is not permissible to fast on the day when menstruation has stopped; because dawn came while she was still menstruating, and God knows best.