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Market Competition

Assisting Another to Sin-Lifnei Iver

In this week’s parasha we read the pasuk “…You shall not place a stumbling block before a blind person…” (Vayikra 19:14). Chazal explain this pasuk as prohibiting one from facilitating another’s sin (Avoda Zara 6b). When are we responsible for another person’s misbehavior? Do Jewish-owned international websites need to be disabled on Shabbos (as is the practice of the website, out of a concern of Chillul Shabbos by visitors of the website? Likewise, can a Jew become a vendor on even if sales may take place on Shabbos?

Is one permitted to (legally) sell weapons, or is he held responsible for crimes committed by his customers? Similarly, is one permitted to provide non-kosher meals to a public institution — old age homes, army bases or prisons, where Jews may be dining? Or would it be enough to simply offer the possibility of ordering kosher meals to those who may be interested?

The Torah prohibition of Lifnei iver, and related, rabbinic prohibitions such as assisting another to commit a sin and doing business on Shabbos are the main topics dealt with in this article.

Market Competition

Selling a product in an exclusive market is judged differently than selling in a competitive market. In the latter, the buyer has the option to buy from Vendor B if he can’t get the product from Vendor A. In the former, he has only one address for his desired product.

The Gemara (Avoda Zara 6b) discusses a case of a nazir, one who took a vow not to drink wine, who seeks to transgress his own vow. The forbidden drink happens to be beyond his reach on the other side of the river. The prohibition of “placing a stumbling block before the blind” is relevant here when one transports the wine across the river to the nazir. However, in the case in which the nazir can reach the wine on his own, one who delivers it to him does not transgress lifnei iver.

Therefore, if one’s website could attract Jewish visitors on Shabbos, but the services or products provided could be found on other websites, there is no Torah prohibition of Lifnei iver in keeping the website active on Shabbos. (If the content is specifically catered to Jews, however, there may be a problem.) The same is true with having a firearms dealership – someone who intends to commit murder will purchase a weapon wherever he can. Therefore, the vendor is not considered to be enabling a customer’s crime (should he commit one) by selling him a weapon. Further on, we will discuss possible rabbinic prohibitions that may be relevant.

On the other hand, a franchisee or other vendor who owns exclusive rights to sell a product or service (e.g. caterers who have contracts with clients such as army bases or old age homes) is considered the only player in its market. As such, the consumer has no alternative regarding where to make his purchase. Therefore, in these cases, providing non-kosher food is prohibited under lifnei iver.

In this case, if one provides kosher food for those who request it, but there are Jews who specifically ask for non-kosher food, there will still be a prohibition of Lifnei iver in providing them with it; every effort must be made to convince them to eat kosher food. If this is impossible, consult a Rav.

A Definite Prohibition

Where the possibility of a Jew coming to perform a transgression is not definite, the Mishna Brura (347:7) writes that there is no problem of encouraging misbehavior. Therefore, one could (legally) sell firearms, since it’s plausible that the guns will be used in a permitted way. Similarly, a caterer who serves both kosher and non-kosher meals to a mixed crowd should of course hope that the Jews take the kosher ones, but is not transgressing an issur in selling non-Kosher food. However, if the probability of Jews taking the non-kosher food is high (for whatever reason), there is a prohibition involved.

The Sefas Emes (Shabbos 3a) writes that unlike other prohibitions whose unintentional violations require kapara (atonement), if one unintentionally places a “stumbling block” before another Jew, no atonement is necessary. So we need not feel bad if we acted in a permitted way, but another ended up doing something prohibited afterwards.

Assisting Another to Commit a Sin

In addition to the Torah prohibition of Lifnei iver, there is a rabbinic prohibition against assisting another to commit a sin. In the example of the Gemara, one who hands the nazir the wine even when the nazir could reach it on his own violates the rabbinic prohibition.

The source for this prohibition is a Mishna (Shviis, 5:9). The Mishna teaches that one is not allowed to help the wife of an am ha’aretz (someone who is not knowledgeable about halacha) to knead dough. The wife of the am ha’aretz is presumed to have tamei keilim. This will cause the challah, the portion of the dough that needs to be separated and given to the Kohen, to prohibitively become tamei.

The Mishna Brura (347:7) discusses a related case of selling a limb of a live animal to a non-Jew, for whom, like his Jewish counterpart, it is also forbidden to eat. The non-Jew in this case can obtain it elsewhere. According to the Magen Avraham there is no prohibition involved with the transaction, while the Gra (Yore Deah 151:1), Chida (Berkey Yosef), and Eminas Shmuel (14) rule that this is forbidden.

The Shach (Yore Deah 151:6), on the other hand, is of the opinion that the prohibition to assist one to commit a sin only pertains to observant Jews, but does not pertain to a non-Jew or non-observant Jew.

Selling on

Among the issues connected to selling through an account on Amazon is that the account can close business deals on Shabbos. This is an issue due to concern that one might come to write down the details of the deal on Shabbos. On Amazon, though, where the buyer does the recording, does this prohibition apply?

A similar case was presented to Rabbi Akiva Eiger (141:159). He was asked about whether money could be given to a Kohen for a pidyon haben (redemption of a firstborn male) before Shabbos with intent that the exchange take effect on Shabbos. Rabbi Eiger leaned towards the view that both the father and the Kohen are in violation of doing business on Shabbos. It’s worth noting that the Netziv (Meromei Sade, Yoma 13a) and the Ksav Sofer (Orech Chayim 46) hold similarly.

The Makne (Kiddushin 45), however, holds that only the buyer in a transaction that takes effect on Shabbos transgresses a prohibition.

Still other Achronim disagree and on a broader level permit automated buying and selling, as long as nothing is actively being done on Shabbos. See Sefas Emes, Eiruvin 39b; Or Someiach, Shabbos 23:12; Toras Chessed, Orech Chayim 13; Emek Yehoshua 9; Imrei Yosher II, 39; Har Tzvi, Orech Chayim I, 126.

Another approach that may render automated e-commerce on Shabbos permissible is the approach of the Imrei Bina (Trumos U’Ma’asros 6). In his opinion, Rabbi Akiva Eiger only forbade the deal because it was tentative and required authorization on Shabbos by both parties to push the deal through. In automated e-commerce, no such authorization is required, so it’s possible that Rabbi Akiva Eiger would have permitted such a purely automated transaction. The Maharashag (II, chapter 117) in fact permits it in this kind of case.

The information provided here can be considered food for thought; for a directive of how to handle a specific situation, please consult a competent halachic authority.

More on Selling Firearms

Selling firearms in itself may be a prohibition. The Mishna (Avoda Zara 16a) writes:

One may not sell them (the gentiles) bears nor lions. In regards to something that can result in injury to members of the public, one may not build together with the gentiles – [e.g.] a basilica, a tribunal, a stadium, or a platform. But one may build with them small platforms and bathhouses. [In the latter case,] once he reaches the arched chamber in the bathhouses where the gentiles erect objects of idol worship, it is prohibited to build.

Included in the prohibition of selling bears and lions is selling ammunition, chains and handcuffs.

In addition, the Shulchan Aruch (Yore Deah 151:5-6) rules that one may not even sell to a Jew any such items if he is suspect to in turn sell them to a non-Jew.

Where Jews live peaceably under foreign rule and the government protects the inhabitants from foreign enemies, one is permitted to provide them with ammunition. Accordingly, the Shach (chapter 23) writes that, in his day, it was accepted to sell ammunition to the non-Jews because it served as a form of protection against enemies who could come to wage war against their city.

Indeed, leaving aside specific times when selling weapons may be allowed, the Torah has a very negative view of those who sell weapons. Regarding the name of one of Lemech’s sons “…Tubal-Cain, who sharpened all tools that cut copper and iron,” (Bereshis 4:22) the Midrash, quoted in Rashi, explains: “Tubal-Cain: He refined the craft of Cain. Tubal is related to the word תַּבְלִין (spices). He “spiced” and “refined” Cain’s craft to make weapons for murderers” [Bereshis Raba 23:3]. Production of weapons makes killing easier and is thereby looked down upon.

With regards to our day, Rabbi Wiesel, shlita, noted that since it is rare for a licensed carrier of firearms to commit a crime in Israel, it is permitted to sell firearms with proper permits. In Israel, possessing a weapon is a matter of self-protection. But where gun violence is rampant (in the US, for example, where gun violence killed nearly 20,000 people in 2020) and crimes are often committed even by those who have license to carry weapons, the halacha is different. One is prohibited to sell firearms in such a case, even if other vendors are also doing so. Again, for guidance in a specific case one should receive help from a competent halachic authority.

More on Non-Kosher Food

As is the case with selling weapons, selling non-kosher food in itself may be problematic. The Mishna in Shviis (7:3) forbids regularly selling non-Kosher meat and animals to non-Jews. On an occasional basis, however, such a sale is permitted (obviously, selling to a non-Jew). Selling cheylev (cattle’s fatty hindquarters) and rabbinically prohibited food items are not included in this ban.

Additionally, one must be careful not to sell foods from which Jews are forbidden to derive benefit, such as meat cooked with milk, non-kosher wine, and chometz that was in a Jew’s possession during Pesach.

It’s interesting to consider that if one has a dish of bacon and eggs, he would be permitted to (on an occasional basis) serve it to a non-Jewish customer, since the Torah prohibition of deriving benefit does not apply to this case. However, if one’s non-Jewish friend gave him a cheeseburger (cow’s meat cooked with milk), it would be forever prohibited to (re)sell it.


The Torah prohibition of Lifnei iver pertains to enabling one to sin when, in his circumstances, he would otherwise not be able to. Chazal added a prohibition consisting of physically assisting another to acquire a forbidden item. Selling an item that can easily be bought elsewhere may be permitted.

Being a party to a deal that takes effect on Shabbos, selling weapons and non-kosher meat involve many halachas, all of which must be taken into account when deciding if a course of action is permissible.

The issue of Lifnei iver is multifaceted, and we strongly urge anyone who finds himself in a situation of possible concern to seek rabbinic guidance.

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