The Mishnah on today’s daf (=page) teaches that a Jewish person can send the hindquarters of a kosher animal to a non-Jew as a present without removing the gid ha-nasheh – the forbidden sciatic nerve – and we do not fear lest the non-Jew will pass the meat on to a Jew who may eat it, since the place of the gid ha-nasheh is clear and no mistakes will be made.
The Gemara understands from the wording of the Mishnah that this is true only if the whole piece of meat is given to the non-Jew. If, however, the meat is cut up, then it cannot be given as a gift to the non-Jew. Several possible explanations are raised by the Gemara to explain why it would be prohibited to give a cut-up piece of meat as a gift to the non-Jew; ultimately the Gemara suggests that it is because of geneivat da’at – fraud. Shmu’el is quoted as ruling that is forbidden to deceive all people, including non-Jews. The Gemara is concerned that a false impression has been created. The non-Jew may be grateful to his Jewish friend who is sending him meat fit for his own table, whereas in reality the meat sent could not be eaten by the Jew since the gid ha-nasheh had not been removed.
According to the Tosefta in Bava Kamma, geneivat da’at (literally, “stealing his mind”) is equivalent to actual theft. The proof to this idea is a passage in Sefer Shmu’el (II Shmu’el 15:6), which states that King David’s son, Avshalom “stole the hearts of the people of Israel.” The Ritva and other rishonim state clearly that misleading anyone – Jew or non-Jew – is a Biblical prohibition. That is clear from the Tosefta that rules that it is forbidden to sell non-kosher animals to a non-Jew who thinks that the meat is kosher. Shmu’el’s addition in our Gemara is that this is true not only in the case of an untruthful sale, but even in a situation where by giving a gift the non-Jew will have a misimpression about the intentions of the person who gave the gift.