The Torah in Parashat Behar commands, “al tonu ish et achiv” (25:14), which forbids selling something for a significantly higher price than its fair market value. Several verses later (25:17), the Torah seems to repeat this command – “ve-lo tonu ish et amito” – though Chazal (Bava Metzia 58b) interpret this second command as referring to “ona’at devarim,” or inflicting emotional pain. Just as it is forbidden to cause a person financial harm through unfair pricing, it is forbidden to cause a person emotional harm.
The Mishna (there in Bava Metzia) gives several examples of ona’at devarim, including inquiring into the price of an item that is for sale without any intention to purchase the item. This knowingly causes the seller pain by raising his false hopes of making a sale.
The Gemara cites a berayta which, like the Mishna, cites various examples of the ona’at devarim prohibition, but this example – showing interest in merchandise one has no interest in purchasing – is attributed to Rabbi Yehuda. The first Tanna cited by the Mishna omits this example, perhaps indicating that these Tanna’im debate the question of whether this practice is included in the prohibition of ona’at devarim. It is perhaps for this reason, as several writers explained, that the Rambam, in discussing the laws of ona’at devarim (Hilkhot Mekhira, chapter 14), omits this example. He may have felt that Rabbi Yehuda’s ruling represents the minority view among the Tanna’im, and according to the majority, expressing interest in merchandise one has no intention of buying does not fall under the prohibition of ona’at devarim.
Possible proof to this understanding may be brought from the Gemara in Masekhet Pesachim (112b), which tells of the ethical teachings presented by Rabbi Yishmael ben Rabbi Yossi to Rabbi Yehuda Ha-nasi. One of these teachings, the Gemara relates, is, “Do not stand over merchandise at a time when you don’t have money.” Seemingly, if this practice violates a Torah prohibition, there would be no need for Rabbi Yishmael to especially instruct his student to avoid it. It appears that at least according to Rabbi Yishmael, expressing interest in merchandise does not violate a strict prohibition, and he was instructing his student to avoid it as a matter of general propriety and sensitivity. This becomes understandable in light of the berayta in Masekhet Bava Metzia which attributes the view that this practice constitutes ona’at devarim to Rabbi Yehuda, indicating that this does not represent the majority opinion.
Most other Rishonim, however, include this practice as an example of ona’at devarim. These include the Rif (in Bava Metzia), the Sefer Ha-chinukh (338), and the Tur (C.M. 228). They apparently felt that although the berayta brings this example of ona’at devarim as a minority position, nevertheless, since it is included in the Mishna, which makes no mention of any debate, this view is the accepted opinion. (Interestingly, the Rambam himself brings this example of ona’at devarim in Sefer Ha-mitzvot (lo ta’aseh 251), despite omitting it in his presentation of the laws of ona’at devarim in Hilkhot Mekhira.)
As for Rabbi Yishmael’s instruction, which implies that expressing interest in merchandise does not violate the Torah prohibition of ona’at devarim, several Acharonim offer a different explanation of that passage. Malbim (here in Parashat Behar), for example, writes that Rabbi Yishmael’s teaching – “Do not stand over merchandise at a time when you don’t have money” – refers to expressing interest in something which the owner will likely offer for free. Rabbi Yishmael speaks of a distinguished Torah scholar who shows interest in something he cannot afford, prompting the owner to offer it to him as a gift out of respect for the sage. This should be avoided, Rabbi Yishmael taught, as a rabbi’s receiving special privileges could easily create a chilul Hashem (defamation of God). Malbim compares Rabbi Yishmael’s teaching with Rav’s famous comment in Masekhet Yoma (86a) that if he would purchase meat from the butcher on credit, this would cause a chilul Hashem, as people might think he received the meat for free. According to this explanation, Rabbi Yishmael’s instruction has nothing at all to do with ona’at devarim, and thus does not prove that expressing interest in merchandise does not violate the ona’at devarim prohibition.