The 242nd prohibition is that we are forbidden from taking as security any objects that are used in food preparation, such as those used for grinding, kneading, cooking, slaughtering animals, or any other type of food preparation.
The source of this prohibition is G‑d's statement (exalted be He), "Do not take an upper or lower millstone as security for a loan, since that is like taking a life as security."
In the words of the Mishneh, "The verse does not refer only to millstones, but to anything used in food preparation, as the verse says, 'since that is like taking a life as security.' "
We now need to explain the statement of our Sages, "A person transgresses for both items, as the verse says, 'Do not take an upper or lower millstone.' " From this, one could be misled into thinking that they count as two mitzvos. This is indicated even more strongly in their statement, "One transgresses one prohibition for the upper millstone and one for the lower millstone."
The explanation of these statements is as follows: if a person takes an object used for food preparation as security, he transgresses this prohibition, as we explained. If he took many articles, of which all are used for preparing food — such as one article that is used for grinding, another that is used for baking, and a third that is used for kneading — he would be committing a separate transgression for each article. This is [obvious and] unnecessary to explain. It is as if the person took one garment as security from Reuven's widow, one from Shimon's widow, and one from Levi's widow, in which case he would be guilty of 3 transgressions.
The explanation of the phrase "both items," is that it refers to a case where both items are used in preparing food, and one cannot be used without the other. In this case, since they are only effective when used together, we would be uncertain whether to count them as one case; or, since they are two articles, to count them as two transgressions. Therefore, our Sages explained to us that the person is punished for two transgressions, even though the act can only be done with the two together — such as the upper and lower millstone, where one cannot be used to grind without the other. If a person took these millstones as security, it would be as if he took a kneading trough and a slaughtering knife, each of which are used for different acts. This is the intention of the phrase, "A person transgresses for both items" — not that they count as two separate mitzvos.
The language of the Sifri regarding this that I've just explained: "Just as the upper and lower millstones are two articles that are used for a single act, and nevertheless each counts as a separate prohibition; so too for any two articles that are used for a single act, each counts as a separate prohibition." This means that although they are used for a single act, each one nevertheless counts as a separate prohibition.
If one transgresses this prohibition and takes the object as security, we take it back from him and return it to the poor person. If the object was lost or burned before he was able to return it, he receives lashes. The same applies to taking a widow's garment as security.
The details of this mitzvah are explained in the 9th chapter of tractate Bava Metzia.
