Commentaire sur Le Lévitique 24:4

המנרה הטהרה THE PURE CANDELABRUM — It was so called because it was made of pure gold. Another explanation is: he shall set the lights in order upon the purity of the candlestick, implying that he must first purify (cleanse) it and remove its ashes beforehand (the words therefore mean: on a clean candlestick; cf., however, Sifra, Emor, Section 13 12 where the word is explained differently).

יערוך את הנרות לפני ה' תמיד, “he shall arrange the lights before Hashem, continually. He must not arrange everything outside the Tabernacle and then carry the menorah into the Tabernacle.

על המנורה הטהורה, “On the pure Menorah, etc.” Nachmanides points out that in Exodus 27,21 where the subject of preparing the oil for the Menorah is first dealt with there is no mention of the Menorah being “pure.” He explains the reason for this as being that that paragraph was not the primary paragraph dealing with the laws concerning the Menorah. When Moses was told in Exodus 27,20: “and you are to command the Children of Israel,” this referred to the details about the oil etc., being revealed to the Israelites eventually. However, here we are dealing with the principal paragraph dealing with the rules governing the use of the Menorah and how it was to be serviced. This is why the words “on the pure Menorah” were added here to tell the Priests that unless the Menorah was in a state of ritual purity the whole procedure could not be performed. This became important when the Hasmoneans recaptured Jerusalem and the Holy Temple from the Greeks and as a result they introduced the festival of Chanukah; and it is important nowadays when we have no Temple, no red heifer, etc. Had the Torah only written the paragraph in Exodus chapter 27 we would have thought that the procedure of preparing oil, etc. was to be performed even in the absence of a Menorah or when the Menorah was temporarily broken.
Sifra Emor 13,12 explains that the words על המנורה הטהורה may also be understood as על טהרה של מנורה, “directly on the Menorah,” i.e. there is not to be any insulating material or other matter between the lights (the containers of the oil and wick) and the golden Menorah. Moreover, the words also imply that the lights are to be prepared and kindled inside the Tabernacle, על המנורה, on the Menorah; lit matches, lit wicks, etc., are not to be brought into the Tabernacle and then be placed on the Menorah, but the whole procedure is to be performed inside the Sanctuary. The word תמיד at the end of the verse means that this procedure overrides the Sabbath and is to be performed seven days a week and even when ritually impure.