Bechoros Daf 13 בכורות דַף 13

The second Perek begins: הלוקח עובר פרתו של עובד כוכבים – if one buys the fetus of an idolator’s cow, or has any of the forms of shared ownership with an idolator listed on Daf 2a, the firstborn cow is exempt from bechor status. Rebbe Oshaya said: ישראל שנתן מעות לעובד כוכבים בבהמתו – if a Yisroel gave money to an idolator for his animal, בדיניהם – it is ruled “according to their laws.” Therefore, אף על פי שלא משך קנה וחייבת בבכורה – even though [the Yisroel] did not perform משיכה on the animal, he acquired it, and it is subject to bechor status. Abaye ultimately explains: בדיניהם שפסקה להם תורה – it means according to the laws which the Torah set for them in the passuk about משיכה: או קנה מיד עמיתך – or buy [movable items] from your fellow’s hand, which implies: מיד עמיתך הוא דבמשיכה – only a purchase from your fellow’s hand is effected with משיכה, הא מיד עובד כוכבים בכסף – but a purchase from an idolator is effected through money.

Rebbe Oshaya also said: עובד כוכבים שנתן מעות לישראל בבהמתו  – if an עכו"ם gave money to a Yisroel for his animal, בדיניהם – it is ruled “according to their laws.” Even though the עכו"ם did not perform משיכה, he acquired the animal, and it is exempt from bechor status. Here, too, Abaye explains that this means according to the laws which the Torah set for them, in the same passuk: וכי תמכרו ממכר לעמיתך – when you sell something to your fellow, implying: לעמיתך במשיכה – a sale to your fellow is effected with משיכה, הא לעובד כוכבים בכסף – but a sale to an idolator is effected through money. In both cases, the Gemara proceeds to prove that the passuk does not mean to require both money and משיכה to effect transactions with an עכו"ם. Nor does it mean that transactions can be effected with an עכו"ם using either money or משיכה, because an עכו"ם’s laws are דומיא דעמיתך – similar to your fellow; מה עמיתך בחדא – just as transactions with your fellow are effected with only one method (משיכה), אף עובד כוכבים נמי בחדא – so too, transactions with an idolator are effected with only one method (כסף).

Ameimar disagrees with Rebbe Oshaya, and says transactions with an עכו"ם are effected through משיכה. The Gemara observes that if he holds like Rebbe Yochanan, that דבר תורה מעות קונות – Biblically, money acquires מטלטלין (and not משיכה), he can explain the exclusion of "לעמיתך" as teaching that, in contrast to a Yisroel, transactions with an עכו"ם are effected with משיכה. However, if he holds like Reish Lakish, that transactions between Jews are effected מדאורייתא with משיכה, how would he darshen the exclusion of "לעמיתך"? The Gemara answers that it teaches: לעמיתך אתה מחזיר אונאה – to your fellow, you must return אונאה, ואי אתה מחזיר אונאה לכנעני – but you do not need to return אונאה to a כנעני (i.e., if you overcharge him, or he undercharges you, by a sixth or more, you need not make compensation). However, the Gemara notes that this derashah is only necessary according to the opinion that גזילו אסור – theft from [a כנעני] is forbidden, but according to the opinion that permits such theft, this law is obvious.