It already says (11:2) that Mozenei Mirmah are a To'evah. Why is this repeated?
R. Yonah: Here it discusses one who has big and small weights and measures. He buys with the big and sells with the small. Rashi (Bava Metzi'a 61b) teaches that one transgresses "Lo Yihyeh Lecha b'Kisecha Even va'Aven" (Devarim 25:13) from when he made [the false weights], even though he did not yet measure and cheat with them. This is brought here, for verse 9 discussed Temimus ha'Lev. Here is a proof that a heart with bad Midos, Hashem does not desire it. It is prepared to make its owner stumble in his deeds. From the roots of Midos sprout branches of sin - "Pen Yesh Bachem Ish Oh Ishah
For he will not remember everyone that he cheated, to return the Ona'ah to them. (PF)
What is the Chidush that both of them are an abomination?
R. Yonah #1: There is a bigger punishment for [buying with] the larger weight or measure, for if you bought, you acquired; if you sold, you lost 1 (Bava Metzi'a 51a). He will be punished also for [selling with] the smaller.
R. Yonah #2: There is a bigger punishment for false weights than for false measures. One can look and contemplate the depth of a measure and understand its Shi'ur 2 .
Malbim: Something can appear evil, but it is not evil based on the intent. E.g. the buyer has different stones to weigh the coins; some weigh more, and some less, and the seller has different Eifos. If he sells with the smaller measure, [the buyer] pays with the lighter coins 3 . Even though he can say Zikisi Libi, for he gives the proper amount, he cannot say Taharti me'Chatasi, due to the appearance. Hashem despises both; the Torah forbids having different weights in every case.
Lev Eliyahu (Bereishis p.124): One who swindles with a false weight, and also one who has a false weight, but he is meticulous not to use it, both of them are abominations. The same applies to Midos - one who leans to a bad Midah, even if it does not express itself in action [is To'avas Hashem]!
I.e. a seller loses even when proper weights and measures are used. It is a greater sin to compound his loss via trickery. However, we say (Nedarim 31b) that both the buyer and seller benefit from the sale of a standard item (it is not in great demand, nor is it hard to sell)! Perhaps Bava Metzi'a means only that the buyer gains more, but also the seller gains, like it says in Nedarim. (Heard from R. Binyamin Karlebach - PF.)
One cannot gauge a rock's weight via sight. Even if he can gauge its volume, he does not know its density. One would not hold another's stone to gauge its weight, for this shows that he suspects him. Alternatively, even if he holds it, most people cannot gauge weights well. (PF)
Bava Metzi'a 51a-b: If a coin is slighter lighter than it should be, it is valid for [everything, including] Pidyon Ma'aser. Only a stingy person [is adamant not to accept it]! Perhaps where many people are stingy, it is harder to spend them, so the buyer and seller could agree that less Peros will be given for lighter coins. (PF)
