259. Weight Watchers: The obligation to ensure that weights and measures are accurate

We spoke in the previous mitzvah of the importance of not shortchanging others in business. The way to do this is by making sure that the tools of our trade – scales, tape measures, quarts, pints, liters, bushels, whatever – are all fair and accurate. If we have inaccurate implements, it’s a foregone conclusion that someone’s going to get shafted.

Our verse ends, “I am God, Who brought you out of Egypt.” The Talmud (Baba Metzia 61b) explains why. Just as God knew everyone’s paternity in Egypt, so that He could punish appropriately during the plague of the first-born, God also knows who has crooked weights and pays back for that as well.

An example of this mitzvah in action is that it is prohibited for a merchant to have weights made of a material that will naturally erode and get lighter.

The reason for this mitzvah is apparent: if we don’t keep accurate measures, it’s inevitable that we will cheat someone, accidentally if not intentionally.

This mitzvah applies to both men and women in all times and places. As with the previous mitzvah, it is discussed in the Talmud in tractates Baba Metzia (61b) and Baba Basra (90a-b) and is codified in the Shulchan Aruch in Choshen Mishpat 231. This mitzvah is #208 of the 248 positive mitzvos in the Rambam’s Sefer HaMitzvos. It is not listed independently in the Chofetz Chaim’s Sefer HaMitzvos HaKatzar, but he does refer to it in his negative mitzvah #83.