John Gill Bible Commentary

Command the children of Israel,.... Moses was the chief magistrate under God, and being clothed with authority from him, had power to command the children of Israel to do what the Lord required of them: that they bring unto thee pure oil olive, beaten, for the light; this was to be at the public expense, and it belonged to the community to supply the priests with oil for the light of the candlestick in the temple, Exo 25:6; and this oil was not to be any sort of oil, as train oil, or oil of nuts, almonds, &c. but oil of olives, and not any sort of that, but the purest, which was the first that was taken from them; it seems there were three sorts, the first of which was pure, and this beaten in a mortar, and not ground in a mill; See Gill on Exo 27:20, to cause the lamps to burn continually; the lamps in the golden candlestick, which were seven, Exo 25:37; or "the lamp", in the singular number, as it is in the original text; the western lamp, which is said to be always kept lighted, from which the rest were lighted when out; though the oil was undoubtedly for the supply of the lamps, that they might burn always, night and day; or from night tonight, as Jarchi; and both on sabbath days and working days, as the Targum of Jonathan.