"From evening until morning" (Exodus 27:21). Give it its measure, so that it shall keep burning and going from evening until morning.
Give the Lamp Its Measure to Burn From Evening Until Morning
Yalkut Shimoni on Torah 378:11
מֵעֶרֶב עַד בֹּקֶר. תֵּן לָהּ מִדָּתָהּ שֶׁתְּהֵא דּוֹלֶקֶת וְהוֹלֶכֶת מֵעֶרֶב עַד בֹּקֶר.