Exodus 27:20-21

Darby^{(i) 20} And thou shalt command the children of Israel, that they bring thee olive oil, pure, beaten, for the light, to light the lamp continually. ²¹ In the tent of meeting outside the veil, which is before the testimony, Aaron and his sons shall dress them from evening to morning before Jehovah: [it is] an everlasting statute, for their generations, on the part of the children of Israel.