Mishnayos Bava Basra Perek 5 Mishnah 11

Rabban Shimon ben Gamliel said: In what case is this statement, that it is necessary to clean a measuring vessel, said? With regard to moist items, which are likely to adhere to the measuring vessels. But with regard to dry goods, which do not adhere to the measuring vessels, one does not need to clean his measuring vessels. And before adding the weights and merchandise the seller is obligated to let the pans of the scale that will hold the merchandise tilt an extra handbreadth for the buyer by adding a weight to that side. If the seller weighed for him exactly, i.e., with the scales equally balanced initially, instead of allowing the scales to tilt an extra handbreadth, he must give the buyer additional amounts [geirumin], an additional one-tenth in the case of liquids sold by weight, and an additional one-twentieth in the case of dry goods. The mishna continues to discuss the correct method of weighing: In a place where they were accustomed to measure merchandise in several stages with a small measuring vessel, one may not measure all the items at once with a single large measuring vessel. In a place where they measure with one large measuring vessel, one may not measure with several small measuring vessels. In a place where the custom is to level the top of the measuring vessel to remove substances heaped above its edges, one may not heap it, and where the custom is to heap it, one may not level it.

אָמַר רַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל, בַּמֶּה דְבָרִים אֲמוּרִים, בַּלַּח. אֲבָל בַּיָּבֵשׁ, אֵינוֹ צָרִיךְ. וְחַיָּב לְהַכְרִיעַ לוֹ טֶפַח. הָיָה שׁוֹקֵל לוֹ עַיִן בְּעַיִן, נוֹתֵן לוֹ גֵרוּמָיו, אֶחָד לַעֲשָׂרָה בַּלַּח וְאֶחָד לְעֶשְׂרִים בַּיָּבֵשׁ. מְקוֹם שֶׁנָּהֲגוּ לָמֹד בַּדַּקָּה, לֹא יָמֹד בַּגַּסָּה. בַּגַּסָּה, לֹא יָמֹד בַּדַּקָּה. לִמְחֹק, לֹא יִגְדֹּשׁ. לִגְדֹּשׁ, לֹא יִמְחֹק: