In the Tent of Meeting, outside the veil that is in front of the Testimony, Aaron and his sons are to tend the lamps before the LORD from evening until morning. This is to be a permanent statute for the Israelites for the generations to come.
Jewish Publication Society of America Version (JPS1917) - Exodus 27:21 >In the tent of meeting, without the veil which is before the testimony, Aaron and his sons shall set it in order, to burn from evening to morning before the LORD; it shall be a statute for ever throughout their generations on the behalf of the children of Israel.