But thou shall have a perfect and just weight, a perfect and just measure shall thou have,.... That is, full weights, and full measures; and such as are alike, and everywhere used, according to the standard of the country; See Gill on Lev 19:36, that thy days may be lengthened in the land which the Lord thy God giveth thee; long life was always reckoned a blessing, and is frequently promised to, obedience, and particularly long life in the land of Canaan; which was a most delightful and fruitful land, and which a man might wish to live long in; deceitful men, are threatened with not living half their days, and such may they be said to be that use false weights and measures, Psa 55:23.