How long should women who do not experience the white discharge wait to ensure purity by dryness? What is the possible duration for women who do not know the number of days of their menstruation, and is it permissible to adopt Abu Hanifa's view that the maximum duration of menstruation is ten days?

A menstruating woman becomes pure by one of two signs: dryness (al-jufuf) or seeing the white discharge (al-qassah al-bayda'). She should not wait until her usual period ends if she sees one of these two signs. However, if the bleeding stops before her usual period expires, the prevalent fatwa (definition) with us is that she must perform ghusl (definition) immediately upon seeing dryness, and she should not wait, based on the saying of Ibn Abbas: "It is not permissible for her, when she sees purity for an hour, except that she performs ghusl." If the blood returns within the possible period (zaman al-imkan), she reverts to being in menses. The possible period is when the duration of the blood and any intervening purity does not exceed fifteen days. Some scholars permit waiting half a day or a full day for certainty, but the first opinion is more cautious. The view of the Hanafis regarding the maximum duration of menses is weak (marjouh), but there is no harm for one who imitates them in adopting it.