Sefer HaChinuch ספר החינוך

To not hold over deficient weights and measures: That we have been prevented, that we not hold over the deficient weights and scales in our homes — and even if we don’t take and give (measure) with them in our purchases and in our sales, lest it be a snare. And about this is it stated (Deuteronomy 25:13), “You shall not have in your pouch alternate weights, larger and smaller.” And so [too] (Deuteronomy 25:14), “You shall not have in your house alternate measures.” And so did they, may their memory be blessed, say in Bava Batra 89b, “It is forbidden for a person to hold over a deficient or oversized weight in the midst of his home, and even if it is [used as a] bedpan for urine.”

And Rambam wrote (Sefer HaMitzvot LaRambam, Negative Commandments 272), “And do not think that they are two [distinct] commandments since they are two negative statements [in the Torah]. Indeed, [the two statements] have come to complete the laws of the commandment, such that two types of size are included — and they are the weight and the measure. [It is] as if it stated, ‘You should not have two sizes, not in measurement and not in weight.’ [It is] like ‘You shall not take interest from loans to your brother, whether in money or food or anything else that can be taken as interest’ (Deuteronomy 23:20) — which is all one negative commandment. As it is not by the duplication of expressions that [the number of] commandments increase, when it is all one matter. And so [too with] ‘no leavened bread shall be found with you, and no leaven shall be found’ (Exodus 13:7), which is [all] one negative commandment, since it is [all] one matter. Rather, [the two expressions] are stated to complete the elucidation of the matter.”

I have written about the roots of this commandment — as is my custom in this book — in the Order of Kedoshim Tehiyu (Sefer HaChinukh 259) regarding the commandment of just scales and the warning (Sefer HaChinukh 258) not to lie with [the scales]. And from there you can see what you need about this [commandment].

And it is practiced in every place and at all times by males and females. And one who transgresses it and holds over a deficient weight or a deficient scale in the midst of his home — and even if he does not ever weigh with them — has violated this negative commandment. And there are no lashes for it, as there is no act [involved] with it; and also, even if he transgressed it and weighed with them, it is given to repayment. And it is already known that we only give lashes for a negative commandment that is not given to repayment.