Mitzvah 258) Not to change measurements
Parshas Kedoshim
“You must not commit an iniquity in justice, in measures, weights or volumes!” (Vayikra 19:35)
It is a negative commandment that one may not cheat in liquid or dry measurements, or in weights. Included in these measurements are also measuring land, or anything else which people measure, like clothes or other things, as it says “You must not commit an iniquity in justice, in measures, weights or volumes!”. Chazal explained that the word “Mesurah” refers to liquid and dry measurements, and that is the smallest measurement. We extrapolate from here that the Torah insisted on correct measures even when they are very small, and even when it is worth less than a Perutah (the smallest coin in Talmudic times).
One who commits an iniquity in measurements is called a sinner and disgusting; excommunicated and an abomination. He causes five things: he defiles the land, profanes the name of Hashem, pushes the Divine Presence aside, cause Jews to fall by the sword and drives them out of their land.
One may not falsify measurements even for a non-Jewish idol-worshipper, and if he did, he has transgressed a negative commandment and must return what he took falsely. It is similarly forbidden to trick non-Jews in calculations, and about this it says “For the abomination of Hashem is anyone who commits iniquity!”
This commandment applies in all times and all places, both to men and women.