Is it obligatory to make up the prayers of the sixth and seventh days after the cessation of menstrual bleeding on the sixth day, and what is the required duration to ensure the cessation of menstruation and begin purification for performing prayer?

Dryness is one of the two signs of purity. So, when a woman observes it after her menstruation, she should perform ghusl and pray, even if her previous habit was to achieve purity with the white discharge. This is the view of the majority of scholars. It is obligatory to make up the prayers that were missed after dryness. If you usually achieve purity with dryness alone, then you should perform ghusl and pray when it occurs. If you see the white discharge, perform ghusl and pray. If your habit is to achieve purity with the white discharge and you observe dryness, you should wait for the white discharge until the end of the chosen time for prayer. If you do not see it, then pray.