הלכה על שמות 27:21

The commandment of arranging lights in the Temple: To prepare perpetual lights in front of God, may He be blessed, as it stated (Exodus 27:21), "Aharon and his sons will arrange it," meaning to say, he will set it up in front of God, may He be blessed. And this is the law of preparing the lights that is mentioned in the Gemara (Yoma 14b).