Sheiltot d'Rav Achai Gaon 167:1שאילתות דרב אחאי גאון קס״ז:א׳
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Haamek Sheilah on Sheiltot d'Rav Achai Gaon 167:16:1העמק שאלה על שאילתות דרב אחאי גאון קס״ז:ט״ז:א׳
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Bava Metzia 58b:10בבא מציעא נ״ח ב:י׳
Likewise, if donkey drivers are asking to purchase grain from someone, and he has none, he may not say to them: Go to so-and-so, as he sells grain, if he knows about him that he never sold grain at all. He thereby causes the donkey drivers and the would-be seller anguish. Rabbi Yehuda says: One may not even cast his eyes on the merchandise for sale, creating the impression that he is interested, at a time when he does not have money to purchase it. Verbal mistreatment is not typically obvious, and it is difficult to ascertain the intent of the offender, as the matter is given to the heart of each individual, as only he knows what his intention was when he spoke. And with regard to any matter given to the heart, it is stated: “And you shall fear your God” (Leviticus 25:17), as God is privy to the intent of the heart.
Pesachim 112b:11פסחים קי״ב ב:י״א
Rabbi Yishmael, son of Rabbi Yosei, commanded Rabbi Yehuda HaNasi with regard to three matters. Parenthetically, the Gemara states that mem, kuf, shin is a mnemonic for the three statements, as it stands for mum, blemish, mekaḥ, a purchase, and ishtekha, your wife. The first matter is: Do not inflict a blemish upon yourself. The Gemara asks: What is the meaning of that statement? The Gemara explains: Do not have a court case against three people, as one will be your opponent and two will act as witnesses and testify against you whatever they wish. And do not stand over and display interest in a purchase when you do not have enough money even for the price you are offering, as this constitutes fraud.
Arukh HaShulchan, Choshen Mishpat 228:2ערוך השולחן, חושן משפט רכ״ח:ב׳
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Shulchan Arukh, Choshen Mishpat 228:4שולחן ערוך, חושן משפט רכ״ח:ד׳
What is affliction with words? A person should not say, “how much are you willing to accept for this item,” when he has no intention of purchasing it. If donkey-riders were looking to purchase grain, one may not say to them to go to so and so when he knows that person has nothing to sell. If someone had repented from his earlier ways, one may not say to him “remember your earlier actions.” If one is the son of converts, one may not say to him, “remember your father’s actions.” If a person was suffering a person may not tell him what Iyov was told by his friends, “is your fear of heaven not your confidence? Do you remember, please, anyone innocent who was destroyed?” If one is asked a question on a certain subject he should not tell someone who is unfamiliar with that subject to give an answer on this matter. The same applies to anything similar.
Shulchan Arukh, Choshen Mishpat 227:26שולחן ערוך, חושן משפט רכ״ז:כ״ו
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