And in the explanation of Allah the Exalted’s statement:“And they ask you about menstruation. Say: It is harm, so keep away from women during menstruation, and do not approach them until they are pure. Then when they have purified themselves, go to them as Allah has commanded you (i.e., intercourse in the front, not the back). Indeed, Allah loves those who repent and loves those who purify themselves.”And the statement of the Prophet (peace and blessings of Allah be upon him) that this is a matter which Allah has decreed for the daughters of Adam. Some of the people of knowledge have said that menstruation first appeared among the Children of Israel. Abu Abdullah (Imam Bukhari, may Allah have mercy on him) says that the hadith of the Prophet (peace and blessings of Allah be upon him) includes all women.

Narrated Al-Qasim: `Aisha said, "We set out with the sole intention of performing Hajj and when we reached Sarif, (a place six miles from Mecca) I got my menses. Allah's Apostle came to me while I was weeping. He said 'What is the matter with you? Have you got your menses?' I replied, 'Yes.' He said, 'This is a thing which Allah has ordained for the daughters of Adam. So do what all the pilgrims do with the exception of the Tawaf (Circumambulation) round the Ka`ba." `Aisha added, "Allah's Apostle sacrificed cows on behalf of his wives."