This is to be understood either,
1. Particularly of the measure or quantity of fine flour, and wine, and oil, which was fixed by God's law. Or
2. Generally of all measures, used either in sacred or civil things, the public standards whereof were kept in the sanctuary or temple; of which see on Exodus 30:13; and therefore the care of keeping them inviolable, and producing them upon occasion, must needs belong to the priests, and under them to the Levites, who were to examine other measures and all things by them, as oft as occasion required, that so the priests might be at more leisure for their higher and greater employments.