Ask about a person to his friend; Reuven was a guest in a synagogue and after a short time Shimon, who rarely came to the synagogue, stood Reuven up in front of the audience and embarrassed Reuven and caused him emotional distress. Reuven said that he would never come to that synagogue in the future. Reuven's friend informed the rabbi of the synagogue about the incident and asked the rabbi to apologize to Reuven and also to instruct the audience to give up their seat in favor of the guests. The rabbi refused to do this to prevent insulting guests in the future. Is he doing the right thing or not? Please provide a source in halakhah or custom.

Shalom u'vrachah, I cannot express an opinion regarding the specific incident, since I do not know all the details. Presumably, the rabbi has his own version of the events, and perhaps Shimon does as well. Instead, I will address the question as it is presented—as a theoretical case. The Shulchan Aruch (Orach Chaim 90:19) rules: "A person should establish a fixed place for prayer and should not change it except when necessary." The Mishnah Berurah (90:60) explains that an area within four amot is considered the same place. From the wording of the Shulchan Aruch, "he should not change it except when necessary," we learn that when there is a genuine need, one may pray somewhere other than one's regular seat. If a guest sits in someone's usual place, this constitutes such a need, and it is proper not to say anything to the guest lest he be embarrassed. Instead, the regular attendee may sit near his usual place, within the four-amah area, if possible (Chashukei Chemed, Berachot 7b; see also Yalkut Yosef, Orach Chaim 90:30, and Piskei Teshuvot 90:24). Nevertheless, one cannot obligate a person to give up his seat. Just as one cannot be required to surrender his home, so too a person has rights to the seat he acquired, and he is not obligated to forgo it. Therefore, if Shimon merely asked the guest to vacate his seat, it may not have been the proper thing to do, but there is no halachic claim against him. However, if he publicly humiliated Reuven, then he certainly acted improperly. Regarding Reuven's friend's requests of the rabbi, I do not understand them. Why should the rabbi instruct others to give up their seats? Nor does he have the authority to compel them to do so—they are under no obligation. Likewise, why should the rabbi personally apologize? Did he do anything wrong? Or perhaps you mean that the rabbi should require Shimon to apologize. Even then, I would ask: why must the rabbi demand this? Is Shimon his child? If Shimon is someone who would accept rebuke, then Reuven's friend himself may gently rebuke him in an appropriate and respectful manner. Further Discussion: We have just emerged from Tisha B'Av, during which many studied the well-known passage in the Gemara (Gittin 55b) concerning Kamtza and Bar Kamtza, whose story led to the destruction of Jerusalem. There, the host publicly humiliated Bar Kamtza and expelled him from the banquet. The Gemara relates that Bar Kamtza reasoned that since the Sages witnessed the incident and remained silent, they must have approved of the host's conduct. This ultimately contributed to the destruction of the Temple. Based on that story, one might argue that in our case the rabbi should have protested rather than remained silent. However, the Maharsha explains there that the Sages remained silent because they were unable to intervene effectively. Likewise, it may be that in our case the rabbi lacked the practical ability to protest. Furthermore, in the story of Bar Kamtza, the protest should have come from the Sages while the incident was taking place. In our case, however, it is possible that the rabbi was not present and did not witness the incident firsthand (see Ben Yehoyada to Gittin 56a). Regarding the case of a guest sitting in someone else's regular seat, the Chashukei Chemed (ibid.) writes that the regular attendee should leave the seat for the guest and pray elsewhere, because of the concern that the guest might be embarrassed. Yalkut Yosef (ibid.) and Piskei Teshuvot (ibid.) write that if a guest sits in someone's regular place, "one should not quarrel over it." Their wording could be understood to mean that one may politely try to ask the guest to vacate the seat, but should avoid arguing with him over it. In my opinion, however, the view of the Chashukei Chemed appears more persuasive—that one should not even point it out to the guest, since doing so may embarrass or offend him.