"There shall not be unto you in your house a measure and a measure": I might think that one should not make a measure of a kav, a tarkav, a half-tarkav, and a quarter tarkav; it is, therefore, written "great and small" — a great which "falsifies" the small, i.e., he should not take (merchandise) with the great and return with the small, (giving the impression that he is using the same measure).

R. Akiva says: Whence is it derived that one should not keep an imperfect measure for use in his own home? From "There shall not be unto you in your house.⁠"

And whence is it derived that one should not be precise (in weighing) in a place where an "extra" is generally given (to the customer), and that one should not give an "extra" in a place where it is customary to be precise? From (Ibid. 15) "a just stone shall there be unto you.⁠"

And whence is it derived that if one said, in a place where it is customary to give an extra: I shall be precise (and deduct the amount of the "extra" from the price); or, in a place where it is customary to be precise: I shall give him an "extra" and deduct something from the price or add something to the price — Whence is it derived that he is not heeded? From "A whole and just stone shall there be unto you.⁠" And whence is it derived that (grain) is not heaped where it is the practice to strike it, and that it is not struck where it is the practice to heap it? From "a just ephah (measure) shall there be unto you.⁠" And whence is it derived that if one said, in a place where it is generally struck: I shall heap it and add to the price; or, in a place where it is generally heaped: I shall strike it and deduct from the price — Whence is it derived that he is not heeded? From "a whole and just measure shall there be unto you.⁠"

Variantly: "and just shall there be unto you": From here it was ruled: The wholesaler should clean the vessels once in thirty days, and the private person, once a year, (so that past adhesions not falsify the weight.) R. Shimon b. Gamliel says: Just the opposite. A shopkeeper cleans his measure twice a week (For a shopkeeper is not required to "drip" three drops as a wholesaler and a homemaker are, and residue remains in the vessel and sticks to it), and he wipes his weights (i.e., he cleans the stones of his scales with which he measures wet things) once a week. And he cleans his scales for every weighing.

"shall there be unto you": Appoint a market commissioner to this end. R. Elazar b. Chananiah b. Chizkiah b. Gurion says: It is written (Ezekiel 46:11) ("the meal-offering,) an ephah (measure) for a bull and an ephah for a ram.⁠" Now is the measure for a bull and a ram and a sheep the same? We are hereby apprised that both the large ephah and the small ephah are called "ephah.⁠"

[End of Piska]