(Mishnah): If a person sent his son to a shopkeeper and he measured out an issur amount of oil and the son paid the money; if he broke the container and lost the money, the shopkeeper is liable. R. Yehudah exempts him because it was with this understanding that the father sent him.

The Chachamim agree that when the container was still in the son's hands and the shopkeeper measured out into it, the shopkeeper is exempt.

A wholesaler must clean his measures once in thirty days (because they are used frequently, many drops stick to them); a private seller must clean them once in 12 months.

R. Shimon ben Gamliel: It is the opposite. (The wholesaler's measures are used often so the drops rarely dry up and stick to the measures.)

The shopkeeper must clean his measures twice per week, his weights once a week and his scale after each use.

R. Shimon ben Gamliel: When is this? When selling liquids; but for solids, he does not need to clean them.

If he gave him the exact weight (as the custom is not to overweigh), he must also give him - a tenth of a litra for every ten litra of liquids and a twentieth of a litra for every twenty litra of dry food bought.

Where the custom is to measure with a small measure, one may not use a big measure (since the buyer will then lose the excess of each unit measured); if it is to measure with a large measure, one may not use a small measure (as the seller will lose out).

Where the custom is to use a level measure, one may not use a heaped measure; if it is to use a heaped measure, one may not use a level measure.

(Gemara) - R. Ba bar Mamal: (When the Mishnah taught (in (g)) that if he gave him the exact, he must also give him - a tenth of a litra for every ten litra of liquids etc.) it means a tenth of a litra from ten litra, which is actually 1/100th , for liquids.

The pasuk states (Vayikra 19, 36), "honest scales and honest stones (measures shall be to you)''. (This implies a warning to you rather than to Beis Din. Another verse states about being careful with weights and measures (Devarim 25:15), "...in order that you shall lengthen your days on the land...''. The Chachamim taught from here that Beis Din do not involve themselves with any mitzvah that has a reward as its fringe benefit (mentioned in the Torah).

Question: Beis Din are required to appoint an angarmus (one who supervises the measures) and you say that?

Answer (R. Bun bar Chiya): The Beraisa should read Beis Din are not punished for its transgression of a mitzvah that has a fringe benefit (mentioned in the Torah).