Yahya related to me from Malik from Hisham ibn Urwa from hisfather from A'isha umm al-muminin that the Messenger of Allah, mayAllah bless him and grant him peace, mentioned Safiyya bint Huyy andhe was told that she had started her period. The Messenger of Allah,may Allah bless him and grant him peace, said, "Perhaps she will delayus." They said, "Messenger of Allah, she has done tawaf," and theMessenger of Allah, may Allah bless him and grant him peace, said,"Then she will not delay us."Malik said that Hisham saidthat Urwa said that A'isha said, "We have publicized that, so why dopeople make their women stay on to their inconvenience? If it were asthey say, more than six thousand menstruating women would still be inMina in the morning, all of them having already done the tawaf al-ifada.' "
USC-MSA web (English) reference: Book 20, Hadith 237
Arabic reference: Book 20, Hadith 935