LEV515 A person buys something in a store, and finalizes the sale in accordance with halachah. Afterward, he shows the item to his friend, to find out whether the item is really worth the price that he paid for it. In response, the friend not only fails to compliment him on his purchase, he also disparages it by telling him that the seller really cheated him. The friend is not particularly meticulous with his assessment at that point, and speaks without determining the item’s precise current market value. This is a mistake, because prices often fluctuate within a short period of time. Furthermore, the friend does not calculate how much the buyer was overcharged, in order to determine whether the price constitutes overcharging according to halachah. Nor does he bother to find out when the deceitful transaction took place, in order to determine whether the window of time for showing the item to a different merchant or to a relative has already passed. If that amount of time did elapse, then there would be no point in notifying the buyer of the matter, for this information would only cause the buyer to develop intense hatred toward the seller. Under such circumstances, were he to inform the buyer of the deception, he would be considered a full-fledged rechilus speaker, who passes negative information from one person to the next. In many cases, the person who tells the buyer about the problem is motivated by his own hatred toward the seller, and it later becomes clear that the item really was worth the amount of buyer paid for it. Often, informing the buyer that he was overcharged causes the seller a financial loss, for the speaker convinces the buyer by saying, “Go return the item and throw it back at him. If you are embarrassed to do it yourself, then send the item back to him with someone else. And if the seller refuses to take it back from you, then don't pay him the money that you owe him for this item or for other merchandise you've bought from him in the past.” (At times, these actions contravene halachah, and therefore constitute outright theft.) When the buyer brings the item back to the seller, and the seller does not want to take it back--for he claims that the buyer is causing him a loss that is halachically unjustified--the two begin to quarrel and berate each other. Take note of how many wrongdoings this rechilus speaker committed. He violated the prohibition of לֹא־תֵלֵ֤ךְ רָכִיל֙ בְּעַמֶּ֔יךָ, “Do not go as a talebearer among your nation” (Vayikra 19:16) (if he was not meticulous to fulfill the conditions we listed above). He violated the prohibition of לִפְנֵ֣י עִוֵּ֔ר לֹ֥א תִתֵּ֖ן מִכְשֹׁ֑ל, “Before a blind person do not place a stumbling block” (Vayikra 19:14), by advising his friend to return the item in contravention of halachah, or by causing him to harm the seller in other ways. He also caused his friend to enter a dispute, in violation of the prohibition of לֹ֤א תֹונוּ֙ אִ֣ישׁ אֶת־עֲמִיתֹ֔, “Do not distress a member of your nation” (Vayikra 25:17), as well as several other prohibitions that are transgressed in the course of a dispute, Hashem should only save us. Therefore, it is highly advisable to refrain from involving oneself in matters like these unless one thoroughly contemplates all that we have discussed. Then, Hashem will help him, so that his actions will not lead to any adverse results.