It is a positive commandment to correct the scales, weights and measures carefully and to be exact in their measure when making them, as Leviticus 19:36 states: "You shall have correct scales...."
Similarly, with regard to the measurement of land, one must be exact according to the principles of geometry. Even a fingerbreadth of land is considered to be a great loss, as if it were filled with saffron.
אמִצְוַת עֲשֵׂה לְצַדֵּק הַמֹּאזְנַיִם וְהַמִּשְׁקָלוֹת וְהַמִּדּוֹת יָפֶה יָפֶה וּלְדַקְדֵּק בְּחֶשְׁבּוֹנָן בִּשְׁעַת עֲשִׂיָּתָן שֶׁנֶּאֱמַר (ויקרא יט לו) "מֹאזְנֵי צֶדֶק" וְגוֹ'. וְכֵן בְּמִדַּת הַקַּרְקַע צָרִיךְ לְדַקְדֵּק בְּחֶשְׁבּוֹן מְשִׁיחַת הַקַּרְקַע עַל פִּי הָעִקָּרִים הַמִּתְבָּאֲרִים בְּכִתְבֵי הַגִּימָטְרִיָּא. שֶׁאֲפִילוּ מְלוֹא אֶצְבַּע מִן הַקַּרְקַע רוֹאִין אוֹתָהּ כְּאִלּוּ הִיא מְלֵאָה כַּרְכּוֹם:
The four cubits that are next to an irrigation ditch need not be measured carefully, and those that are next to a river bank are not measured at all, for they belong to the public domain.
באַרְבַּע אַמּוֹת הַסְּמוּכִין לֶחָרִיץ מְזַלְזְלִין בִּמְשִׁיחָתָן וְהַסְּמוּכִים לִשְׂפַת הַנָּהָר אֵין מוֹשְׁחִין אוֹתָן כְּלָל מִפְּנֵי שֶׁהֵן שֶׁל בְּנֵי רְשׁוּת הָרַבִּים:
A person who measures land should not measure the portion of one partner in the summer and of the other in the winter, because a rope will contract in the summer. Therefore, if the measurement was made with a rod, with iron chains or with the like, the differences in season are of no consequence.
גוְהַמּוֹדֵד אֶת הַקַּרְקַע לֹא יָמֹד לְאֶחָד בִּימוֹת הַחַמָּה וּלְאֶחָד בִּימוֹת הַגְּשָׁמִים מִפְּנֵי שֶׁהַחֶבֶל מִתְקַצֵּר בִּימוֹת הַחַמָּה. לְפִיכָךְ אִם מָדַד בְּקָנֶה אוֹ בְּשַׁלְשֶׁלֶת שֶׁל בַּרְזֶל וְכַיּוֹצֵא בָּהֶם אֵין בְּכָךְ כְּלוּם:
Weights should not be made of iron, lead or other metals of that nature, for they rust and become reduced in weight. One should make them from marble, glass, diamond and the like.
דאֵין עוֹשִׂין מִשְׁקָלוֹת לֹא שֶׁל בַּרְזֶל וְלֹא שֶׁל עוֹפֶרֶת וְלֹא שֶׁל שְׁאָר מִינֵי מַתָּכוֹת כָּאֵלּוּ מִפְּנֵי שֶׁמַּעֲלִין חֲלוּדָה וּמִתְחַסְּרִין. אֲבָל עוֹשִׂין שֶׁל צְחִיחַ סֶלַע וְשֶׁל זְכוּכִית וְשֶׁל אֶבֶן שֹׁהַם וְכַיּוֹצֵא בָּהֶן:
The stick used to level the top of a dry measure should not be made of a gourd, because it is too light, nor of metal, because it is too heavy. Instead, it should be made of olive wood, walnut, box wood, sycamore wood or the like.
האֵין עוֹשִׂין אֶת הַמַּחַק לֹא שֶׁל דְּלַעַת מִפְּנֵי שֶׁהוּא מֵקֵל וְלֹא שֶׁל מַתֶּכֶת מִפְּנֵי שֶׁהוּא מַכְבִּיד. אֲבָל עוֹשֵׂהוּ שֶׁל זַיִת וְשֶׁל אֱגוֹזִים וְשֶׁל שִׁקְמָה וְשֶׁל אֶשְׁכְּרוֹעַ וְכַיּוֹצֵא בָּהֶן:
Mishneh Torah (Moznaim)
Featuring a modern English translation and a commentary that presents a digest of the centuries of Torah scholarship which have been devoted to the study of the Mishneh Torah by Maimonides.
The stick used to level the top of a dry measure should not be made with one side narrow and one side thick. One should not level a measure slowly, bit by bit, for in doing so the seller is cheated, nor should it be leveled in one fell swoop, for by doing so the purchaser is cheated.
ואֵין עוֹשִׂין אֶת הַמַּחַק צִדּוֹ אֶחָד קָצָר וְצִדּוֹ אֶחָד עָבֶה. וְלֹא יִמְחֹק מְעַט מְעַט מִפְּנֵי שֶׁמַּפְחִיתוֹ לַמּוֹכֵר. וְלֹא יִמְחֹק בְּבַת אַחַת מִפְּנֵי שֶׁמַּפְחִיתוֹ לַלּוֹקֵחַ:
One may not bury weights in salt so that their weight will be reduced, nor may one heat while measuring a liquid.
This applies even if the measure is very small, for the Torah was concerned with even the slightest deviation from an honest measure, as implied by the mention of a mesurah in Leviticus 19:35. A mesurah is a very tiny measure, merely a thirty-third of a log.
זאֵין טוֹמְנִין אֶת הַמִּשְׁקָלוֹת בְּמֶלַח כְּדֵי שֶׁיִּפְחֲתוּ. וְלֹא יַרְתִּיחַ בְּמִדַּת הַלַּח בְּעֵת שֶׁמּוֹדֵד. וַאֲפִלּוּ הָיְתָה הַמִּדָּה קְטַנָּה בְּיוֹתֵר. שֶׁהֲרֵי הַתּוֹרָה הִקְפִּידָה עַל הַמִּדּוֹת בְּכָל שֶׁהוּא שֶׁנֶּאֱמַר (ויקרא יט לה) "וּבַמְּשׂוּרָה" וְהִיא מִדָּה אַחַת קְטַנָּה מִשְּׁלֹשִׁים וּשְׁלֹשָׁה בְּלוֹג:
Sellers of scrap iron and the like should construct the scale they use in the following manner. The balance that the person who is weighing holds in his hands should hang freely in the air for at least three handbreadths, and should be three handbreadths above the ground. The length of the center pole and the length of the cables should be twelve handbreadths.
חמוֹכְרֵי עֲשָׁשִׁיּוֹת שֶׁל בַּרְזֶל וְכַיּוֹצֵא בָּהֶן צָרִיךְ לִהְיוֹת חוּטֵי הַמֹּאזְנַיִם שֶׁאוֹחֵז הַשּׁוֹקֵל בְּיָדוֹ תָּלוּי בַּאֲוִיר שְׁלֹשָׁה טְפָחִים וּגְבוֹהִין מִן הָאָרֶץ שְׁלֹשָׁה טְפָחִים וְאֹרֶךְ קְנֵי הַמֹּאזְנַיִם וְאֹרֶךְ הַחוּטִים שְׁנֵים עָשָׂר טֶפַח:
A scale used by wool merchants and glass merchants should be constructed in the following manner. The balance should hang freely in the air for at least two handbreadths and should be two handbreadths above the ground. The length of the center pole and the length of the cables should be nine handbreadths.
טמֹאזְנַיִם שֶׁל מוֹכְרֵי צֶמֶר וְשֶׁל מוֹכְרֵי זְכוּכִית יִהְיֶה אֹרֶךְ הַחוּטִים שֶׁהֵן תְּלוּיִין בּוֹ שְׁנֵי טְפָחִים וּגְבוֹהִין מִן הָאָרֶץ שְׁנֵי טְפָחִים וְהַקָּנֶה וְהַחוּטִין אָרְכָּן תִּשְׁעָה טְפָחִים:
A scale used by an ordinary storekeeper and a house-owner should be constructed in the following manner. The balance should hang freely in the air for at least one handbreadth, and should be one handbreadth above the ground. The length of the center pole and the length of the cables should be six handbreadths.
ימֹאזְנַיִם שֶׁל חֶנְוָנִי וְשֶׁל בַּעַל הַבַּיִת יִהְיֶה אֹרֶךְ הַחוּט שֶׁהֵן תְּלוּיִים בּוֹ טֶפַח וּגְבוֹהִין מִן הָאָרֶץ טֶפַח וְהַקָּנֶה וְהַחוּטִין אָרְכָּן שִׁשָּׁה טְפָחִים:
The cables on which the balance is hung, and similarly the cables of the scales used to weigh gold and used by merchants of purple fabric should be three fingerbreadths long and should be three fingerbreadths above the ground. No standard measure was given for the length of the balance and the length of its chains; it depends on the desire of the person doing the weighing.
יאהַחוּט שֶׁתּוֹלִין בּוֹ הַפֶּלֶס וְכֵן חוּט מֹאזְנַיִם שֶׁל זָהָב וְשֶׁל מוֹכְרֵי אַרְגָּמָן טוֹב אָרְכּוֹ שָׁלֹשׁ אֶצְבָּעוֹת וּגְבוֹהִין מִן הָאָרֶץ שָׁלֹשׁ אֶצְבָּעוֹת וְאֹרֶךְ הַפֶּלֶס וְאֹרֶךְ הַשַּׁלְשְׁלָאוֹת שֶׁלּוֹ כְּפִי מַה שֶּׁהוּא רוֹצֶה:
What is the source that teaches us that one must tip the balance in favor of the purchaser when his purchase is being weighed for him? Deuteronomy 25:15 states: "You shall have a perfect and just weight." The Torah's statements can be interpreted to mean: "Justify your balance from what you have and give it to him."
יבמִנַּיִן שֶׁחַיָּב הַמּוֹכֵר לְהַכְרִיעַ לַלּוֹקֵחַ בְּעֵת שֶׁשּׁוֹקֵל לוֹ שֶׁנֶּאֱמַר (דברים כה טו) "אֶבֶן שְׁלֵמָה וָצֶדֶק יִהְיֶה לָּךְ" אָמְרָה תּוֹרָה צַדֵּק מִשֶּׁלְּךָ וְתֵן לוֹ:
How much should the seller tip in the purchaser's favor? With regard to liquid measure, one hundredth of the amount purchased. With regard to dry measure, one four-hundredth of the amount purchased.
What is implied? If he sold him ten pounds of a liquid measure, he should give him one tenth of a pound as an extra amount. If he sold him twenty pounds of a dry measure, he should give him an extra twentieth of a pound. This ratio should be followed regardless of whether the amounts involved are great or small.
יגוְכַמָּה בְּלַח אֶחָד לְמֵאָה וּבְיָבֵשׁ אֶחָד לְאַרְבַּע מֵאוֹת. כֵּיצַד. מָכַר לוֹ עֶשֶׂר לִיטְרָא לַח נוֹתֵן לוֹ גֵּירוּמִין אֶחָד מֵעֲשָׂרָה בְּלִיטְרָא. וְאִם מָכַר לוֹ עֶשְׂרִים לִיטְרִין יָבֵשׁ נוֹתֵן לוֹ גֵּירוּמָיו אֶחָד מֵעֶשְׂרִים בְּלִיטְרָא. וְכֵן לְפִי חֶשְׁבּוֹן זֶה בֵּין רַב בֵּין מְעַט:
When does the above apply? In a place where it is customary to sell by looking at the scale. In a place where it is customary to actually tip the balance, one must tip it at least a handbreadth in favor of the purchaser.
ידבַּמֶּה דְּבָרִים אֲמוּרִים בְּמָקוֹם שֶׁנָּהֲגוּ לִמְכֹּר עַיִן בְּעַיִן. אֲבָל בְּמָקוֹם שֶׁנָּהֲגוּ לְהַכְרִיעַ חַיָּב לְהַכְרִיעַ לוֹ טֶפַח:
If the seller had to weigh ten pounds for the purchaser, the purchaser should not say: "Weigh them out one at a time and tip the balance each time." Instead, the seller may weigh out all ten at once and tip the balance only once for the entire amount.
טוהָיָה שׁוֹקֵל לוֹ עֶשֶׂר לִיטְרִין לֹא יֹאמַר לוֹ שְׁקל אַחַת אַחַת וְהַכְרַע אֶלָּא שׁוֹקֵל לוֹ עֲשָׂרָה בְּבַת אַחַת וְהֶכְרֵעַ אֶחָד לְכֻלָּן:
In a place where it is customary to measure with a small measure, one should not measure with a large one. In a place where it is customary to measure with a large measure, one should not measure with a small one.
Where it is customary to even off the measure, one should not sell a heaping measure and raise the price, nor where it is customary to give a heaping measure should one sell a level measure and reduce the price. Instead, one should measure according to the local custom.
טזמָקוֹם שֶׁנָּהֲגוּ לָמֹד בְּדַקָּה לֹא יָמֹד בְּגַסָּה. בְּגַסָּה לֹא יָמֹד בְּדַקָּה. לִמְחֹק לֹא יִגְדּשׁ וְיוֹסִיף בְּדָמִים. וְכֵן אִם נָהֲגוּ לִגְדּשׁ לֹא יִמְחֹק וְיִפְחֹת מִן הַדָּמִים. אֶלָּא מוֹדֵד כְּמִנְהַג הַמְּדִינָה:
When the inhabitants of a locale desire to increase the size of the measures or weights, they should not increase them more than a sixth. For example, if a kav held five measures, they may establish it as holding six. They should not, however, establish it as holding more than six.
יזבְּנֵי מְדִינָה שֶׁרָצוּ לְהוֹסִיף עַל הַמִּדּוֹת אוֹ עַל הַמִּשְׁקָלוֹת לֹא יוֹסִיפוּ יֶתֶר עַל שְׁתוּת. שֶׁאִם הָיָה הַקַּב מֵכִיל חֲמִשָּׁה וַעֲשָׂאוּהוּ מֵכִיל שִׁשָּׁה הָרְשׁוּת בְּיָדָן. יֶתֶר עַל שִׁשָּׁה לֹא יַעֲשׂוּ:
A wholesale merchant must clean his measures once every 30 days. A house-owner must do this every twelve months, and a storekeeper twice a week. Once a week, he must wash his weights, and he should clean the balance after every time that he weighs, so that it will not rust.
יחהַסִּיטוֹן מְקַנֵּחַ אֶת מִדּוֹתָיו אַחַת לִשְׁלֹשִׁים יוֹם. וּבַעַל הַבַּיִת אַחַת לִשְׁנֵים עָשָׂר חֹדֶשׁ. וְהַחֶנְוָנִי מְקַנְּחָן פַּעֲמַיִם בְּשַׁבָּת. וּמְמַחֶה מִשְׁקְלוֹתָיו פַּעַם אַחַת בְּשַׁבָּת וּמְקַנֵּחַ מֹאזְנַיִם עַל כָּל מִשְׁקָל וּמִשְׁקָל כְּדֵי שֶׁלֹּא יַחְלִידוּ:
A person who desires to weigh three-fourths of a pound of meat should place a pound weight on one side of the balance and place the meat and a quarter-pound weight in the other side of the balance. If one said that he should place a half-pound weight and a quarter-pound weight on one side and the meat on the other side, it is possible that the quarter-pound weight will fall without being seen by the purchaser.
יטהַמְבַקֵּשׁ לִשְׁקל שְׁלֹשָׁה רְבִיעֵי לִיטְרָא נוֹתֵן לִיטְרָא בְּכַף מֹאזְנַיִם וְהַבָּשָׂר וּרְבִיעַ לִיטְרָא בְּכַף שְׁנִיָּה שֶׁאִם אַתָּה אוֹמֵר נוֹתֵן חֲצִי לִיטְרָא וּרְבִיעַ לִיטְרָא בְּכַף אַחַת שֶׁמָּא יִפּל רְבִיעַ הַלִּיטְרָא וְאֵין הַלּוֹקֵחַ רוֹאֵהוּ:
The court is obligated to appoint police in every city and town to inspect the stores periodically, correct the scales and measures, and set the prices. They are permitted to beat any person who possesses an unjust measure or weight or an improper balance according to his capacity, and to fine him as the court sees fit to enforce the matter.
Whenever a person raises prices and sells at a higher price, he may be beaten and compelled to sell at the ordinary market price.
כחַיָּבִין בֵּית דִּין לְהַעֲמִיד שׁוֹטְרִים בְּכָל מְדִינָה וּמְדִינָה וּבְכָל פֶּלֶךְ וּפֶלֶךְ שֶׁיִּהְיוּ מְחַזְּרִין עַל הַחֲנֻיּוֹת וּמְצַדְּקִין אֶת הַמֹּאזְנַיִם וְאֶת הַמִּדּוֹת וּפוֹסְקִין הַשְּׁעָרִים. וְכָל מִי שֶׁנִּמְצָא עִמּוֹ מִשְׁקָל חָסֵר אוֹ מִדָּה חֲסֵרָה אוֹ מֹאזְנַיִם מְקֻלְקָלִין יֵשׁ לָהֶם רְשׁוּת לְהַכּוֹתוֹ כְּפִי כֹּחוֹ וּלְקָנְסוֹ כְּפִי רְאוֹת בֵּית דִּין לְחַזֵּק הַדָּבָר. וְכָל מִי שֶׁמַּפְקִיעַ אֶת הַשַּׁעַר וּמוֹכֵר בְּיֹקֶר מַכִּין אוֹתוֹ וְכוֹפִין אוֹתוֹ וּמוֹכֵר כְּשַׁעַר הַשּׁוּק: