Exodus 27:21 in the King James Version
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.
Context
20 “You shall command the children of Israel, that they bring to you pure olive oil beaten for the light, to cause a lamp to burn continually.
21 In the Tent of Meeting, outside the veil which is before the covenant, Aaron and his sons shall keep it in order from evening to morning before the LORD: it shall be a statute forever throughout their generations on the behalf of the children of Israel.