הלכות גניבה

When a person weighs for a colleague using weights that are less than the weights accepted by the people in that country, or he measures using a measure that contains less than the measure used by people in that country, he violates a negative commandment, as Leviticus 19:35 states: "Do not act deceitfully with regard to a judgment concerning measures, weights and liquid measures."

Although a person who measures with an inaccurate measure or weight is a thief, he is not required to make a double payment of the stolen amount. All that is necessary is to give the proper measure of the article that was sold. Lashes are not given for the violation of this transgression, because the thief is obligated to make financial restitution.

Whoever possesses an imperfect measure or weight in his home or store violates a negative commandment, as Deuteronomy 25:13 states: "You shall not have in your pocket two sets of weights...." One may not even use the imperfect measure as a chamber pot. For even if one does not use the imperfect measure oneself to buy and to sell, another person who does not know that it is imperfect may come and use it as a measure.
Lashes are not administered for the violation of this transgression, because it does not involve a deed.

If a standard seal was affixed to all the measures and weights in a city, and the imperfect measure did not have such a seal, it is permitted to leave it for other household purposes.
Similarly, when a sela became blemished at its side, a person should not use it as a weight, nor should he cast it among his pieces of scrap metal, nor should he drill a hole in it and hang it around his son's neck, lest another person come and make it appear as a weight. Instead, one should grind it into powder, cut it into small pieces, pulverize it, or throw it into the Dead Sea.

If the size of a sela was reduced to the extent that it was halved, it may be used. If it was reduced to less than half or more than half, it should be cut until it becomes a half.
If it was reduced by less than one sixth of its worth, it may be used for buying and selling, but not as a weight. The reason it may be used is that most people will forgo any loss that is less than a sixth.

A person should make his measures the size of a se'ah, half a se'ah and a quarter of a se'ah, a kav, half a kav, a quarter of a kav, an eighth of a kav and a twenty-fourth of a kav. He should not, however, make a measure of two kabbim, lest it be mistaken for a quarter of a se'ah, which is a kav and a half.
Similarly, with regard to liquid measure, one should make a hin, half a hin, a third of a hin, a quarter of a hin, a log, half a log, a quarter of a log, an eighth of a log and a sixty-fourth of a log.
The Sages did not forbid one from making a third of a hin and a quarter of a hin, although they could be confused with each other, because there were such measures in the Sanctuary from the time of Moses our teacher onward.

Whether a person deals with a Jew or a gentile, if he measures or weighs with a measure that is lacking, he transgresses a negative commandment and is obligated to return the difference.
Similarly, it is forbidden to deceive a gentile with regard to an account; instead, one must reckon carefully with him, as Leviticus 25:50 states: "You should reckon with his purchaser."
This applies with regard to a gentile who is under your control; surely it applies to one who is not under your control. A person who performs such deceit is included among those about whom Deuteronomy 25:16 says: "They are an abomination unto God, all who do these things, all who act crookedly."

Similar principles apply regarding the measurement of land. If a person deceives a colleague with regard to the measurement of land, he transgresses a negative commandment, as implied by Leviticus 19:35: "Do not act deceitfully with regard to a judgment concerning measures...."
"Measures" refers to the measurement of land. The verse is saying that one should not act deceitfully with regard to any judgment, be it a judgment concerning measures, one of weights or one involving a tiny liquid measure, the size of a mesurah.

When the members of a company are exact in their dealings with each other, and they exchange one portion of a sacrificial offering for another, or they borrow food and then return its equivalent, they transgress the prohibition against false measures, false weights and false amounts if they do not return the exact amount. If the exchange takes place on a festival, it is also a transgression of the prohibition against borrowing and repaying on a festival.

A person who usurps the property boundaries of a colleague and includes even a fingerbreadth of a colleague's landed property in his own property transgresses. If he acts openly, by the power of force, he is a robber. If he acts with stealth, he is a thief.
If he usurps a colleague's property in Eretz Yisrael, he transgresses two negative commandments: the prohibition against either theft or robbery, and the prohibition against moving a property boundary. One is liable for the transgression of this negative commandment only in Eretz Yisrael, for Deuteronomy 19:14 states: "Do not usurp the property boundaries of a colleague... in the heritage that you will acquire...."

The punishment for the person who uses false measures is greater than the punishment for licentious sexual behavior, for this is a sin between a person and his colleague, and this is a sin between a person and God.
Whoever denies the mitzvah of just measures is considered as if he denied the exodus from Egypt, which is the first of God's commandments. Conversely, one who accepts the mitzvah of just measures is considered as if he acknowledges the exodus from Egypt, which brought about all of God's commandments.