Rabbi Levi said: Blessed actions bring blessing upon those responsible for them and cursed actions bring a curse upon those responsible for them: “You shall have a whole and just weight, [you shall have a whole and just measure]” (Deuteronomy 25:15). If you have done so, you will have something to take, something to give, something to buy, and something to sell.18This is derived from the repetitive use of the phrase “you shall have” (Etz Yosef).
Cursed actions bring a curse upon those responsible for them: “You shall not have in your pouch different weights, large and small. You shall not have in your house different measures, large and small” (Deuteronomy 25:13–14). If you have done so, you will not have something to take, something to give, something to buy, and something to sell. The Holy One blessed be He said: ‘I said: Do not make large and small measures, and you did; as you live, that person [you] will not have enough even for a small one.’
Likewise, “You shall not make with Me gods of silver or gods of gold, [you shall not make for yourselves]” (Exodus 20:20). If you do so, as you live, there will not be enough even for those of wood and of stone.