What is the ruling on the fast of a woman who had sexual intercourse with her husband at night and forgot to perform ghusl until the time of Fajr entered upon her, and she fasted that day while she was in a state of janabah? And is she required to make up (qada’) the fast or repeat it?

Being in a state of major ritual impurity (janabah) does not affect the validity of the fast. The fast of a person in a state of janabah is valid, even if they intentionally delayed the ritual bath (ghusl) or forgot about it. However, any prayers performed after the state of janabah and before performing ghusl must be repeated, because ritual purity is a condition for the validity of prayer.