Exodus 27
20 Ref Give orders to the children of Israel to give you clear olive oil for the lights, so that a light may be burning there at all times.
21 Ref Let Aaron and his sons put this in order, evening and morning, before the Lord, inside the Tent of meeting, outside the veil which is before the ark; this is to be an order for ever, from generation to generation, to be kept by the children of Israel.