Mrs. Cooper rightly earned the title “bargain buyer.” She combed the advertisements of her local stores weekly and knew just where to buy each item that week at the best price.

Mrs. Cooper had just finished shopping in Pathmark, where tuna fish was on sale. She packed a case in her car and went on to the Kosher Store, where meat was on sale.

While waiting on line, Mrs. Cooper met someone from her shul, Mrs. Fleisher, with a shopping cart containing thirty cans of tuna. “Is tuna on sale here?” Mrs. Cooper asked her.

“No,” replied Mrs. Fleisher. “However, I’m hosting a lot of people for seudah shelishis this week, so I need a lot of tuna.”

“I just picked up a case of tuna at Pathmark priced at three for $2,” Mrs. Cooper said. “You may want to buy the tuna there.”

“Thanks a lot for telling me!” Mrs. Fleisher exclaimed. “Watch my wagon for a minute, while I return the tuna to the shelf.” She removed the tuna from the shopping cart and returned it.

The Kosher Store manager, who stood nearby and overheard the discussion, gave Mrs. Cooper a disapproving look. Although he didn’t say anything, his frown made her wonder whether she was correct to tell Mrs. Fleisher about the Pathmark sale.

Mrs. Cooper came home and asked her husband what he thought. “I have this dilemma all the time,” she said. “I could tell every customer where they could get a better bargain!”

“I guess that until Mrs. Fleisher pays for the tuna, there’s no problem in her returning it to the shelf,” he said. “I understand the ethical dilemma, though. You might want to hear Rabbi Dayan’s perspective.”

Mrs. Cooper called Rabbi Dayan and asked, “When I see someone in the process of buying something, can I tell her where she can buy it cheaper?”

“There are two conflicting responsibilities here,” replied Rabbi Dayan. “There is a prohibition against causing damage to the storeowner. This includes not only direct damage, but also indirect damage (grama). On the other hand, there is a responsibility to spare the customer from loss, which is an extension of hashavas aveidah” (C.M. and Gra 378:1).

“So how do we deal with this?” asked Mrs. Cooper.

“The Gemara (B.B. 21b) indicates that when someone is expecting sure revenue, such as a fisherman closing in on a certain fish, thwarting him is considered damage,” replied Rabbi Dayan. “The Chasam Sofer (C.M. #379) extends this to a customer who has already decided to purchase. In that case you should not help the customer by causing the storeowner damage. However, if the customer is still deliberating whether or not to buy the item, the storeowner cannot consider the purchase as sure revenue. Therefore, the mitzvah of hashavas aveidah would warrant sparing the customer the extra cost” (Mishpetei HaTorah, Hashavas Aveidah #8).

“Are there other relevant factors?” asked Mrs. Cooper.

“If the customer initiates the dialogue and asks, you must respond with honest advice,” replied Rabbi Dayan. “Also, you can advise a customer who is your relative, even if she already decided to buy the item; there is a priority to look out for the welfare of your relatives. In addition, if the storeowner is demanding an unfair price or cheating on quality, you should inform the customer; this is not considered causing the storeowner damage. In all cases, though, you must not speak lashon hara about the store. You can say, ‘The item is cheaper elsewhere,’ but should not say, ‘Prices here are always sky-high!’” (see Chofetz Chaim, Rechilus 9:10).

“Does it matter who owns the store?” asked Mrs. Cooper.

“If the store is not Jewish-owned, you can alert a Jewish customer of possible savings even when already on line to pay,” replied Rabbi Dayan. “Damaging a non-Jew is also prohibited, but discouraging potential customers in this way is not considered causing damage to them. Therefore, the mitzvah of hashavas aveidah to the fellow Jew remains in force. However, if store personnel are nearby and this will cause a chillul Hashem, it is not allowed!” (See Pischei Choshen, Geneivah 9:[1]; Nezikin 9:[2].)