Does Ibn Abbas's statement, "It is not permissible for her, when she sees purity for an hour, except to perform ghusl," mean that the bleeding must stop for at least an hour, or is it sufficient for it to stop for five minutes or less to indicate purity? And are sleeping hours counted within the dry period, or must dryness be confirmed for an hour after waking up, especially when relying on dryness as a sign of purity?

The correct meaning of Ibn Abbas's statement is the obligation for a menstruating woman to perform ghusl (definition) immediately upon seeing purity, even if for a short time, and it is not a condition for a specific period of dryness to pass. Some scholars are of the opinion that a menstruating woman should wait a day and a half if the cessation occurs during her usual period, because blood flows and then stops, and this is the more preponderant view according to Ibn Qudamah. So, if a woman sees purity, she is pure, performs ghusl, and prayer and fasting become obligatory upon her. If you do not become aware of dryness until after waking up, consider yourself pure upon seeing the dryness and do not wait for an hour to pass after waking up.