Musar zu Wajikra 19:36

Similarly, they said (Bava Metzia 49a): "[What is taught by the verse (Vayikra 19:36):] 'A just Hin [shall you have', surely 'Hin' is included in 'Ephah'?] [Answer] it is to teach you that your 'yes' [hen] should be just and your 'no' should be just! [Abaye said: That means that one must not speak one thing with the mouth and another with the heart]".

מאזני צדק אבני צדק הין צדק . You shall have an honest balance, honest weights, etc." (19,36). These laws are designed to emphasize how far we must distance ourselves from robbery. The very fact that the Torah chose to call such weights by the adjective צדק, indicates that it considers a person engaged in weighing or measuring as though he were a judge presiding over litigation and required to pronounce fair judgment. Civilization is based on justice as we know from Rabbon Shimon ben Gamliel in Avot 1,18. The reason that the Torah quotes three examples of such weights or measures, i.e. איפה, אבני and הין, may relate to the three levels of our spiritual existence, our soul, i.e. נפש, רוח, נשמה.

מאזני צדק אבני צדק . Terms such as מאזני צדק, are all references to mystical concepts. This is an additional reason to be most careful not to tamper with weights and measures.