The Rabbis defined geneabt da'at (stealing other people mind) as a situation in which I mislead other people to think favorably about me or about an action I did (see here).
Some times however, there are borderline circumstances, in which a positive but misleading impression is leftinvoluntarily. The Rabbis argued about the merits of this matter.
A real example: It was customary that when a Rabbi would come to town his students or colleagues would go to welcome him before he reached the city. It happened that two rabbis, Raba and Rab Safra, left their city to take care of some personal matters and to their surprise on the way they met a distinguished rabbi, Mor Zutra, who was coming into their city. Mor Zutra thought that they came to welcome him, and with a deep sense of gratitude he said: "I'm so honored that such distinguished Rabbis like you have come all the way to welcome me!". Rab Safra, which was famous for being extremely straightforward and truthful said: "Well, the truth is that we did not know that you were coming. We were in our way for a different matter and we happened to meet you. However, if we would have known of your coming, we would have received you with more honors". Later on Raba questioned Rab Safra's attitude and said to him: "Why did you have to hurt Mor Zutra who thought that we were coming to honor him?". Raba added "In this case we did not initiate anything proactively with the intention of leaving a false big impression on him! We did not want to mislead him. But now we have actually hurt him and embarrass him!".
When the other Rabbis heard and analyzed this case they thought that Raba was right and they asserted that the prohibition of causing a positive false impression on someone applies when we initiate the misleading action, but if the other person brings himself to that impression, and especially in this type of situations bordering with embarrassment, then we do not need to rectify the false positive impression we left.
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