Bekhorot 13B

מה ״עמיתך״ באחת, אף גוי נמי באחת.

Just as property is acquired from your counterpart through only one act of acquisition, i.e., pulling, so too, property is acquired from a non-Jew through only one act of acquisition, i.e., payment of money.

אמרי: ולאמימר דאמר משיכה בגוי קונה, הניחא אי סבר לה כרבי יוחנן דאמר: דבר תורה מעות קונות, משיכה לא, אהני ״לעמיתך״⁠ — לעמיתך בכסף, לגוי במשיכה.

The rabbis said: And according to the opinion of Ameimar, who says that pulling effects acquisition in the case of a non-Jew, this works out well if he holds in accordance with the opinion of R' Yoḥanan, who says: By Torah law, money effects acquisition, but pulling does not. If Ameimar accepts R' Yoḥanan’s opinion, then it can be derived from the phrase “of your counterpart” that transactions with your counterpart, i.e., a Jew, are effected through payment of money, whereas transactions with a non-Jew are effected by pulling.

אלא אי סבר לה כריש לקיש, דאמר: משיכה מפורשת מן התורה, לעמיתך במשיכה, ולגוי במשיכה, ״לעמיתך״ למה לי?

But if Ameimar holds in accordance with the opinion of Reish Lakish, who says: The act of acquisition of pulling is explicit in the Torah, then the halakha is that transactions with your counterpart are effected by pulling, and transactions with a non-Jew are also effected by pulling. Accordingly, why do I need the phrase “of your counterpart”?

אמרי: לעמיתך אתה מחזיר אונאה, ואי אתה מחזיר אונאה לגוי. לגוי ⁠— מ״אל תונו איש את אחיו״ נפקא!

The rabbis said in explanation: The phrase “of your counterpart” does not teach a halakha with regard to the method of acquisition. Rather, it is referring to the latter part of the verse: “And if you make a sale to your counterpart, or buy of your counterpart’s hand, a man should not exploit his brother” (Leviticus 25:14). The verse is derived as follows: You must return the sum of exploitation to your counterpart, but you do not need to return the sum of exploitation to a non-Jew. The Talmud rejects this suggestion: The exemption from returning the sum of exploitation to a non-Jew is derived from the latter part of the verse alone: “A man should not exploit his brother.” A non-Jew is not included in the category of “his brother.” Accordingly, the phrase “of your counterpart” remains extraneous.