Is it necessary to use a cotton swab or tissue to check for purity (ṭahārah) after menstruation, and is she sinful if she does not do so? Is it permissible to wait twenty-four hours after the cessation of blood to perform ghusl without checking? And if the color of the discharge is not known when verifying menstruation, can the woman choose between the colors she is unsure about?

A woman ascertains purity from menstruation by one of two signs: the white discharge (al-qassah al-bayda') or dryness (al-jufuf). The white discharge is a white fluid that follows menstruation. Dryness means that if a piece of cotton is inserted, it comes out clean, with no trace of blood, yellowish discharge, or brownish discharge on it. A woman must check for purity in this manner and not merely by looking at her clothes. If she doubts whether purity has occurred, the default assumption is that menstruation persists. If purity is ascertained by dryness, it is permissible to wait for a day and a half after seeing purity, because the nature of blood is to flow and then stop. The preponderant opinion is that normal secretions after the cessation of blood are not considered, and that any yellowish or brownish discharge a woman sees after achieving purity is not considered menstruation as long as it is outside her customary period.