Menstrual Periods
Bukhari :: Book 1 :: Volume 6 :: Hadith 318
Narrated Mu'adha:
A woman asked 'Aisha, "Should I offer the prayers that which I did not offer because of menses" 'Aisha said, "Are you from the Huraura' (a town in Iraq?) We were with the Prophet and used to get our periods but he never ordered us to offer them (the Prayers missed during menses)." 'Aisha perhaps said, "We did not offer them."