Leviticus 24:2
Command the children of Israel, that they bring unto thee pure oil olive beaten for the light, to cause the lamps to burn continually. Command the children of Israel, that they bring unto thee pure oil olive beaten for the light, to cause the lamps to burn continually.
The lamps commanded were kept burning day and night to supply light, for the sanctuary apartments had no windows. Their light filled both the holy place and the most holy place. It was reflected from the gold-plated boards and from the sacred furniture. It shone upon the richly colored curtains until the whole sanctuary appeared glorious, with a beauty like the colors of a rainbow.