What is the ruling on the fast of a woman who purified herself from menstruation at night and fasted during the day, then a small amount of blood came out of her during urination during the day, knowing that she had completed her usual days of menstruation?

Recurrent blood is considered menstrual if the period between the start of the first bleeding and the end of the second bleeding does not exceed fifteen days, and whatever is forbidden for a menstruating woman becomes forbidden due to it. The day on which blood appears, if it does not exceed fifteen days when combined with previous bleeding and purity, is considered menstruation, and fasting on that day is not valid.

Some jurists are of the opinion that any increase beyond the usual period is considered irregular bleeding (istihadah (definition)) that does not prevent prayer and fasting unless it recurs three times, provided that the total period from the beginning of the first bleeding to the end of the renewed bleeding does not exceed fifteen days. If the period exceeds this, it is considered istihadah, and the woman reverts to her usual cycle.