C. F. Keil and Franz Delitzsch on Leviticus 19:35-36

Lev 19:35-36

As a universal rule, they were to do no wrong in judgment (the administration of justice, Lev 19:15), or in social intercourse and trade with weights and measures of length and capacity; but to keep just scales, weights, and measures. On ephah and hin, see at Exo 16:36 and Exo 29:40. In the renewal of this command in Deu 25:13-16, it is forbidden to carry “stone and stone” in the bag, i.e., two kinds of stones (namely, for weights), large and small; or to keep two kinds of measures, a large one for buying and a small one for selling; and full (unadulterated) and just weight and measure are laid down as an obligation. This was a command, the breach of which was frequently condemned (Pro 16:11; Pro 20:10, Pro 20:23; Amo 8:5; Mic 6:10, cf. Eze 45:10).