Sefer HaChinuch ספר החינוך

To not cheat in measures, and all measures are included: To not cheat in liquid and dry measures, and not with scales; and included in measures is also the measuring of lands; and anything that is measured by people, such as clothes and that which is similar to them — as it is stated (Leviticus 19:35), “You shall not pervert justice with measures of length, weight or capacity (mesurah).” And they, may their memory be blessed, explained (Bava Metzia 61b) that mesurah is a liquid and a dry measure; and it is the smallest measure, as it is one thirty-third of a log. And we learn from this that the Torah is concerned about the smallest amount with measures; meaning to say that even though the Torah was only concerned about [the value of] a small coin with other thefts, regarding measures, it was concerned about the smallest amount.

And the explanation of the verse is thus: “You shall not pervert justice” — and what is justice that is learned here? It is the “measures of length, weight or capacity.” And they, may their memory be blessed, learned (Sifra, Kedoshim, Chapter 8:5) from this that the verse mentioned justice here since the measurer is called a judge. And if he lies about the measure, it is like he corrupts the judgment and it is called perversion, disgusting, anathema and abomination. And he causes five things that are said about a judge: he defiles the land; profanes God; removes the Divine Presence; brings Israel down with the sword; and exiles them from their Land. And they emphasized the stringency of this commandment further and said (Bava Batra 88b), that its punishment is greater than the punishment for forbidden sexual relations; as [the latter] is between man and the Omnipresent and [the other] is between man and his fellow.

The root of this commandment is well-known, as I have written in the positive commandment in this Order (Sefer HaChinukh 259).

From the laws of the commandment is that which they said (Bava Metzia 61b) that one who measures or weighs perversely — even though he is stealing without a doubt — does not pay double payment, but rather pays that which he caused him to lack from the measure or the weight. And so [too,] that which they, may their memory be blessed, said (Bava Metzia 52a) to guard this commandment, that one should not make a sela that has been damaged into a weight, lest it get damaged further and the weight will be lacking; and he should not leave it in a place that others can [find and] make it into a weight. And that which they spoke at length about this, to say that if it lacked and stood at exactly half, he can keep [it]. And that which they said [that] a person can make his measurements a seah and a half seah, etc.; but he should not make them two kav, so that it not be mixed up with a quarter seah, which is one-and-a-half kav. And so [too,] with liquid measures, one can make a hin and a half hin, etc. — as it is found in a bereita in Bava Batra 89b.

And that which they said that one who measures land with a rope not measure it for one in the summer and for the other in the winter, because the rope contracts in the summer. And that which they said (Bava Batra 117b) that every person must be very exacting in the measurement of land, since there are many differences in the measurement of land between a mountain and a valley; and one must also also investigate the [differences] between the circles, the rectangles and the angles in it. And also many other matters which are elucidated in the books of the wisdom of mathematics and geometry that distinguish between a right angle, a broad angle and a narrow angle — and these are the three shapes ([pictured here] a right angle, a broad angle and a narrow angle); between a triangle of three equal sides (equilateral), a triangle in which only two sides are equal, and it is called a triangle of equal legs (isosceles), and a triangle in which none of the sides are equal, which is called of varying sides (scalene); between a rectangle that is an even square, a rectangle that is elongated, a rhombus and a rhomboid. And there are several aspects to these — a large parchment could not contain [them] due to the many shapes that the masters of the wisdom of arithmetic and sizes — that are called engineers — have made about these matters. And we must be very careful about all aspects in the measurement of land.

And remember with this that the principles that the Sages, may their memory be blessed, set down regarding matters of mathematics — such as that which they said (Eruvin 57a), “Any ell in a square is an ell and two-fifths in diagonal”; and so [too,] “Everything that has three handbreadths in its circumference has a width of one handbreadth”; and so [too,] “How much more is a square than a circle? One-fourth”; and similar to these principles — they, may their memory be blessed, did not say with complete exactitude, but rather in approximation. And therefore do not rely on it in the division of things among people. And do not wonder, how did they write things that were not exact, since they are men of truth, that God stands in their assembly. As they only needed the calculations for the perimeters of Shabbat or the planting of forbidden mixtures or their planting of trees, and similar to these things; and in this, that which they were not exact about it brings us to a stringency and does not damage any person’s money. And nonetheless, they testified in most of these places that the calculation is not precise there. As they said in each and every place according to what is fit about it, “That is that it is not precise, and it is not precise for stringency,” and similar to this that they informed us in every place; such that we not attribute lack of concern or knowledge to them in any thing of this. And the rest of the details of the commandment are in [Bava] Batra and in other places. (See Tur, Choshen Mishpat 230.)

And [it] is practiced in every place and at all times by males and females. And one who transgresses it and lies about measures of length, weight or capacity has transgressed a negative commandment. But we do not administer lashes for it, because it is given to repayment. And (Ramban) [Rambam], may his memory be blessed, wrote (Mishneh Torah, Laws of Theft 7:8) that if one lied in measures even to a gentile that worships idolatry, he has transgressed a negative commandment and he is obligated to return [it]. And likewise is it forbidden to fool gentiles in calculations, as it is stated (Leviticus 25:50), “And calculate with his owner” — even if he is subjugated under your hand; all the more so towards a gentile that is not subjugated under your hand. And behold, it states (Deuteronomy 25:16), “For it is an abomination of God [...] anyone who does perversion” — in any case.