Is repentance obligatory for delaying prayer until the end of its time when the onset of menstruation is expected, and is prayer immediately obligatory upon its expected onset, which may last for days? And is it obligatory not to delay making up missed prayers when the onset of menstruation is expected?

It is not permissible to delay prayer until the last part of its time when one expects an impediment to performing it, such as menstruation. This applies if the occurrence of the impediment is highly probable. One who is highly probable to experience menstruation must hasten to pray. As for missed prayers, many scholars say they must be made up immediately. However, according to those who say that making up prayers can be done at leisure, delaying is not forbidden when menstruation is expected.