Responsa of Rema — Siman 10:4

The third great principle is found in the Midrash (Torat Kohanim, Parashat Behar): “When you sell something to your fellow or buy…” From here the Torah teaches that if you come to buy, buy from your fellow, and the same applies to selling. It is explicitly stated that even if the aforementioned sage were merely an ordinary person, he would still prevail in judgment and the law would be on his side—how much more so now.

One cannot argue that this applies only when the non-Jew and the Jew offer equal value and price, but if the non-Jew offers a lower price, it would be permitted to buy from him to gain profit. These claims are also baseless, for we learn in the chapter “Eizehu Neshech” (Bava Metzia 72a): Rav Yosef taught, “If you lend money to My people”—your people and a non-Jew, your people come first; a poor person and a wealthy one—the poor comes first, etc. The Gemara asks: your people and a non-Jew—your people come first—isn’t that obvious? It answers: Rav Nachman said in the name of Rav Huna, the teaching is necessary even regarding lending to a non-Jew with interest, as it says “to a foreigner you may lend with interest”; nevertheless, this does not override the positive commandment of “if you lend money to My people.”

All the more so in our case, where the sage has merited that his claim be first. One also cannot argue that this applies only where one does not incur an actual loss but merely forgoes profit; whereas in a case of actual loss, like here, one need not prioritize a Jew. This distinction is discussed in the chapter “Mi Shehechshich” (Shabbat 153a): one may give his purse to a non-Jew, etc. The Gemara says that Rava taught this applies only to one’s purse, but not to a found object. From here we see a distinction between loss of principal and loss of profit.

Similarly, the Semag cites the Yerushalmi regarding Chol HaMoed that something is only considered a loss if it involves loss of principal. I say that these cases are indeed considered loss, for it is explicitly taught in the first chapter of Avodah Zarah (20a) and in Pesachim (21b): “You shall not eat any carcass; to the stranger within your gates you shall give it, that he may eat it, or sell it to a non-Jew.” This teaches giving to a convert and selling to a non-Jew; how do we know one may also sell to a convert? From “you shall give it or sell it.”

Thus it concludes, as Rashi explains, that the verse refers back to the convert mentioned earlier: “to the convert you shall give it and he shall eat it, or sell it.” The Gemara then asks: how do we know giving to a non-Jew is allowed? From the phrase “you shall give it… or sell it to a non-Jew,” which Rashi explains is interpreted to include both possibilities regarding the non-Jew. Rabbi Yehuda, however, says the verse should be taken literally: to a convert by giving, or to a non-Jew by selling.

Thus we may say that Rabbi Meir and Rabbi Yehuda only disagree about whether a verse is needed to establish that the convert takes precedence, but all agree that the convert indeed comes first—even if one incurs a loss of principal, he is still obligated to fulfill “to the convert within your gates you shall give it.” The same applies here: every person is obligated to fulfill “from your fellow”—your fellow comes first. We may even learn from here that even if the non-Jew offers a lower price, one’s fellow still takes precedence. Therefore, no further argument is needed: this sage has rightfully secured his position to be first in selling his books.