THE OIL FOR THE LAMP.
(20) Thou shalt command the children of Israel that they bring thee pure olive oil. — This instruction had been already given (Exodus 25:2; Exodus 25:6), only not with such particularity. “Oil” had been required, but not “pure olive oil beaten.” By this is meant the best possible olive oil — that which was obtained by “beating,” or pounding in a mortar; which was free from various impurities that belonged to the oil crushed out, after the ordinary fashion, in a mill.
To cause the lamp to burn always — i.e., every night without intermission. Josephus says that three lights were kept burning both night and day (Ant. Jud., iii. 7, § 7); but there is nothing in Scripture to confirm this. The tabernacle would have received sufficient light during the daytime through the entrance curtain, which was of linen (Exodus 26:36), not to mention that the curtain may, when necessary, have been looped up. The lighting of the lamps every evening is distinctly asserted in Exodus 30:8; their extinction in the morning appears from 1 Samuel 3:3.