How many hours of complete dryness are required to ensure purification, and is it a condition for the dryness to continue for a day and a night, given that there is sometimes complete dryness for hours?

Menstruation is the well-known blood that women experience, and it includes blood, yellowish discharge (ṣufrah), and brownish discharge (kudrah). A woman should not rush to consider herself pure as long as she sees yellowish or brownish discharge, based on the saying of Aisha (may Allah be pleased with her): "Do not rush until you see the white discharge (al-qaṣṣah al-bayḍā’)."

If the cessation is not complete and some yellowish or brownish discharge remains, then it is not purity. However, if the cessation is complete, meaning neither yellowish nor brownish discharge remains, then this is a sign of purity, and she should perform ghusl (definition) (ritual bath) and pray.

Any brownish or yellowish discharge a woman sees after achieving purity is not considered menstruation, based on the saying of Umm Atiyyah: "We did not consider brownish or yellowish discharge after purity as anything." Similarly, a drop or two of blood is not subject to the rulings of menstruation.