Sublime

As stated there (ibid.:11), the obligation to return the article or the money applies only when both parties are Jewish. Although it is forbidden to deceive a gentile regarding the value of merchandise, it is not forbidden to take advantage of an error the gentile makes on his own.

Nevertheless, if when dealing with a gentile, the gentile makes an error in counting, weighing or measuring merchandise and is willing to purchase it for more than its value, it is not necessary to correct him and inform him of its true worth. Although this standard of righteousness is required when dealing with a Jew, it is not mandatory when

forbidden to deceive a gentile even with regard to a matter that will not cause him a loss, e.g., to sell him meat from an animal that

When, by contrast, a gentile64 errs concerning the value of merchandise or the value of a coin, it is not necessary to notify him of his error.

It is forbidden to mix a small amount of [inferior] produce into a large amount of superior produce so that [the inferior produce] will not be recognized95 and [then] sell the entire quantity under the presumption that it is [all] of higher quality.96

[Using a false weight or measure] is not comparable to taking unfair gain from [a gentile which is allowed]. For in that instance, [the gentile] sees what he is buying and errs on his own with regard to the value of the merchandise. [Taking advantage of a judgment] error [of this type made by a gentile] is permitted, as is [taking possession of] an

[The above leniency is granted,] provided he does not intentionally purchase the majority from a superior source so that he will develop a reputation that he purchases everything from a superior source, while also purchasing some from an inferior source and mixing them together in a manner that [the inferior ones] will not be noticed.100