Sahih Bukhari, Chapter: Menstrual Periods

'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 Taw-af (Circumambulation) round the Ka'ba." 'Aisha added, "Allah's Apostle sacrificed cows on behalf of his wives."