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 not stop fasting now, but then he (peace and blessings be upon him) would leave fasting for such a long period that we would think he will not fast anymore. And he (peace and blessings be upon him) used to recite Surah Bani Isra'il and Surah Az-Zumar every night.