Abd Allah said: It does not please me that her husband approaches her during the days in which she prays, because we cannot be certain that it is not menstrual blood. She only prays and fasts as a precaution for the act of worship, and refraining from intercourse is also a precaution, so it becomes obligatory just as prayer is obligatory. If the increase exceeds the maximum [duration] of menstruation, then it is istihadah (irregular bleeding), and she should not sit (refrain from prayer) for any time other than her habit under any circumstances. An example of this is a woman whose habit is three days at the beginning of every month. She sees blood for five days at the beginning of the month, or she sees two days from the end of the previous month and her usual three, or she is pure for three [days] and sees three (9) or more than that, or less, before or after them, or she is pure on the first day and sees three after it or more (10), or she is pure for two days and sees two days after them or more (10), or she sees blood for two days at the end of the month and one day at the beginning of it, and similar scenarios. In all these cases, she does not sit (refrain from prayer) except for the first [days] of the month until it is repeated, based on the statement of the Prophet (peace and blessings of Allah be upon him): "Sit for the duration that your menstruation used to keep you (11)." This is because she has a habit, so she is returned to it, like the woman with istihadah. Abu Hanifah said: What she sees before the habit is not menstruation until it is repeated twice, and what she sees after it is menstruation. Al-Shafi'i said: All of it is menstruation, as long as it does not exceed the maximum of menstruation. This is stronger in my view, because 'A'ishah, may Allah be pleased with her, used to have women send to her the little container in which there was yellow and brownish discharge, and she would say: "Do not be hasty until you see the white discharge (12)." Its meaning is: Do not be hasty with the ghusl (full ablution) until the blood stops, the yellow and brownish discharge goes away, and nothing remains exiting from the place, such that if a piece of cotton were inserted, it would come out white. If she did not count the increase as menstruation, ghusl would be incumbent upon her when the habit ends, even if the blood is still flowing; because the Lawgiver (al-Shari') attached rulings to menstruation without defining it, so it is known that He referred people in this matter to their custom ('urf). It is the custom among women that whenever a woman sees blood that is fit to be menstruation, she considers it menstruation, even if their custom was to consider the habit in the manner mentioned.