Musnad Ahmad 788:148

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, from 'Amr ibn Murrah, from Abu 'Ubaydah, from Abu Musa, who said: The Messenger of Allah (peace and blessings of Allah be upon him) stood among us with five words and said: "Verily, Allah the Exalted does not sleep, and it does not befit Him to sleep. But He lowers the scale and raises it. The deeds of the night are raised to Him before the deeds of the day, and the deeds of the day before the deeds of the night. His veil is the light; if He were to remove it, the splendors of His Face would burn whatever of His creation His sight reaches."