434. Weights and Measures

62:8 The Torah tells us (Deuteronomy 25:13-15), “You may not have a large weight and a small weight in your bag; you may not have a large measure and a small measure in your house. You must only have full and righteous weights and full and righteous measures.” The phrases “in your bag” and “in your house,” which are apparently superfluous, have been explained by the Sages of the Talmud (Baba Basra 89a) to mean that one will not end up with money in his pocket thanks to false weights, nor possessions in his house from using false measures. One will only prosper from using honest tools in his business. Furthermore, the Sages advised (Talmud Niddah 70b) that if a person wishes to become wealthy, he should act honestly in business and ask Hashem for success as He is the one to whom all wealth truly belongs (as per Haggai 2:8).

62:9
A person should be careful to weigh and measure generously so that the customer actually gets a little extra. The Torah tells us (Deuteronomy 25:15) “you shall have a full and righteous measure.” The Talmud understands the word “righteous” to mean at one’s own expense (Baba Basra 88b).