Exodus 27:20-21

And thou shalt command the children of Israel, that they bring thee pure oil olive beaten for the light, to cause the lamp to burn always. {to burn: Heb. to ascend up} In the tabernacle of the congregation without the vail, which {is} before the testimony, Aaron and his sons shall order it from evening to morning before the LORD: {it shall be} a statute for ever unto their generations on the behalf of the children of Israel.