Humaid says that a person asked Hazrat Anas (may Allah be pleased with him) about the night prayer of the Prophet (peace and blessings be upon him), so he replied: "We could see the Prophet (peace and blessings be upon him) praying at whatever time of the night we wished to see him praying, and if we intended to see him sleeping, we could see him sleeping as well. Similarly, in some months the Prophet (peace and blessings be upon him) would fast continuously to the extent that we would think he would not leave any fast, and at other times he would leave fasting to the extent that we would say perhaps now the Prophet (peace and blessings be upon him) will not fast anymore."