Sayyidah Aisha (may Allah be pleased with her) narrates that the Messenger of Allah (peace and blessings be upon him) would sometimes fast so frequently that we would say he will never stop fasting, but then he (peace and blessings be upon him) would leave fasting for such a long period that we would think he will never fast again. And he (peace and blessings be upon him) used to recite Surah Bani Isra'il and Surah Az-Zumar every night.