Rav Pappa says: It is a balance scale for blacksmiths, who weigh heavy pieces of metal.

Rabbi Mani Bar Pattish says: Just as the Sages said with regard to the prohibition of the scales that one may not use a scale that does not meet the criteria listed in the baraita, so too they said that this applies with regard to their ritual impurity. In other words, if the cords and pole are not attached in the proper manner, they are not susceptible to ritual impurity as part of the scale.

The Gemara asks: What is this statement teaching us? We learned in a mishna (Kelim 29:5): With regard to the rope from which the scales are suspended, if the balance scale belongs to a storekeeper or to homeowners it must be one handbreadth in length for it to be susceptible to ritual impurity. Why, then, is the statement of Rabbi Mani Bar Pattish necessary? The Gemara answers: Although the mishna in tractate Kelim discusses the rope from which the scales are suspended, it was still necessary for Rabbi Mani Bar Pattish to mention the halakha with regard to the scale’s lever and cord, which we did not learn about in that mishna.

§ The Sages taught: One may not prepare weights of tin [ba’atz], nor of lead, nor of a metal alloy [gisteron], nor of any other types of metal, because all of these deteriorate over time and the buyer will ultimately pay for more merchandise than he receives. But one may prepare weights of hard rock and of glass.

The Sages further taught: One may not prepare the leveler, used to remove the excess from the mouth of a vessel, from a gourd, because it is a light material and does not level effectively, thereby causing a loss for the seller. And it may not be made of metal, because it weighs down and removes too much of the merchandise, leading to a loss for the buyer. But one may prepare it from the wood of an olive tree, or of a nut tree, or of a sycamore tree, or of a boxwood tree,which are of medium weight.

The Sages taught: One may not prepare the leveler in such a manner that one of its sides is thick and one other side is thin, because in such a case the two sides will not level equally. Furthermore, one may not level all at once, by a single quick movement, as one who levels all at once acts in a manner that is bad for the seller and good for the buyer, because he removes less of the excess than one who levels in the regular fashion. And conversely one may not level little by little, i.e., with several slow movements, as this is bad for the buyer and good for the seller.

Rabban Yoḥanan ben Zakkai said with regard to all these halakhot: Woe to me if I say them, and woe unto me if I do not say them. If I say them, perhaps swindlers will learn new methods of cheating of which they were previously unaware. And if I do not say them, perhaps swindlers will say: Torah scholars are not well versed in our handiwork. A dilemma was raised before the Sages: Did Rabban Yoḥanan ben Zakkai decide to say these halakhot in public or did he not say them? Rav Shmuel bar Rav Yitzḥak says: He said them, and he said them on the basis of this verse: “For the ways of the Lord are right, and the just walk in them; but transgressors stumble over them” (Hosea 14:10).

§ The Gemara further discusses weights and measures. The Sages taught: “You shall do no unrighteousness in judgment, in measure [bammidda], in weight, or in measure [uvamesura]” (Leviticus 19:35). The baraita defines these terms: “In measure [bammidda],” this is referring to measuring land, teaching that in order to measure land in a just manner one may not measure for one person in the summer when the measuring rope has become dry and short, and for one other individual in the rainy season, when the measuring rope is wet and limp, and therefore stretches more. “In weight” means that one may not cover his weights in salt, as salt erodes the weights, causing a loss for the buyer. “Or in measure [bamesura]” means that one may not cause liquid he is measuring to foam by pouring it speedily, as this results in a loss for the buyer, who receives less of the liquid than the amount for which he paid.

The Gemara notes: And it can be inferred by means of an a fortiori inference that if in the case of a mesura, which is a measure equivalent to merely one thirty-sixth of a log, the Torah was particular that one must measure honestly, so too, a fortiori, one must be careful in the case of one hin, and a half-hin, and a third-hin, and a quarter-hin, which is twelve log, and one log, and a half-log, and a quarter-log, and a half-tomen, i.e., one-sixteenth of a kav, and even an ukla, a smaller unit, as defined below.

Rav Yehuda says that Rav says: It is prohibited for a person to keep in his house a measure that is too small or too large than its supposed volume or weight, and this is the case even if he does not measure with it but simply uses it as a chamber pot for urine. Rav Pappa said: We said this prohibition only with regard to a place where measures are not stamped with the government’s seal, which confirms that the measure is accurate. But in a place where the measures are stamped, if the buyer does not see the seal he would not take the merchandise. Since they could not be used dishonestly, one is permitted to utilize these measures for other purposes. And in a place where measures are not stamped as well, we said that it is prohibited to keep these measures in one’s house only in a place where they do not inspect measures to see if they are fit for use. But if they do inspect measures, we have no problem with it.

The Gemara comments: And that is not so; one is never permitted to keep incorrect measures in his house, as sometimes it happens that one measures at twilight, when people are hurried, and consequently it happens that the buyer takes the merchandise despite the fact that it was measured with an incorrect measure. This is also taught in a baraita: A person may not keep in his house a measure that is too small or too large, even if it is used as a chamber pot for urine. But he may prepare measures in accordance with the established format: Measurements of a se’a; a tarkav, which is three kav or one-half of a se’a; and a half-tarkav, which is one and one-half kav; and a kav; and a half-kav; and a quarter-kav; and a tomen, which is one-eighth of a kav; and a half-tomen;