And Abu Al-Zinad said: The matters of religion and the rulings of Shari'ah are often contrary to opinion and analogy, and it is necessary for Muslims to follow them. Among these is the ruling that a menstruating woman should make up the fasts but not make up the prayers.

Narrated Abu Sa`id: The Prophet said, "Isn't it true that a woman does not pray and does not fast on menstruating? And that is the defect (a loss) in her religion."