If a woman’s menstruation stops while she is at work or travelling and she is not able in that situation to take a bath (ghusl), is she allowed to miss the obligatory prayers (i.e., defer them until the time when she can take a bath)?
Prayer (salah) is the firmest of the obligations placed on believing men and women. They must do the obligatory prayers within the time when they are due. If a Muslim is willing but simply not able to do wudu’ or ghusl within the time when a prayer is due, then she or he is commanded to do tayammum instead of wudu’ or ghusl. Then, after tayammum, she or he must pray within the time set for the prayer due.
As is well-known, for women during their menstruation the obligation of salah is suspended. When a woman’s menstruation ends, she must do ghusl; then she can do the prayers again as normal. The obligation of salah resumes not with the action of her doing ghusl, but with the stopping of her menstruation. Now if this happens when she is in a situation such that she cannot do ghusl – for example, if she is at work, or a student attending lectures, or travelling – then she should do tayammum and do the prayer within the time when it is due. Then, when she comes home or goes to some other place where she is able to do ghusl, she should do so. She does not need to repeat the prayer or prayers that she prayed with tayammum because the prayer with tayammum is valid whenever there are valid reasons for doing tayammum instead of wudu’ or ghusl.
God says in the Qur’an: “O you who believe! Approach not the salah (the prayer) when you are in a drunken state until you know (the meaning) of what you utter, nor when you are in a state of janabah, (i.e. in a state of sexual impurity and have not yet taken a bath) except when travelling on the road (without enough water, or just passing through a mosque), till you wash your whole body. And if you are ill, or on a journey, or one of you comes after answering the call of nature, or you have been in contact with women (by sexual relations) and you find no water, perform tayammum with clean earth and rub therewith your faces and hands (tayammum). Truly, Allah is Ever Oft-Pardoning, Oft-Forgiving.” (al- Nisa’ 43)