Sahih Muslim Book 003, Hadith Number 0661.
Chapter : It is obligatory for menstruating woman to complete the abandoned fats, but not the abandoned prayers.
It is reported from Mu'adha that she asked 'Aisha: Should a menstruating woman complete the prayer (abandoned during the menstrual period)? 'Aisha said: Are you a Hurariya? The wives of the Messenger of Allah (may peace be upon him) have had their monthly courses, (but) did he order them to make compensation (for the abandoned prayers)? Muhammad b. Ja'far said: (Compensation) denotes their completion.