(Devarim 18:3) "And this shall be the judgment of the Cohanim": We are hereby taught that the priestly gifts (shoulder, cheeks, and maw) are "law" (to the end of extracting them by court order from a thief who stole them from a Cohein who had acquired them from hefker [ownerless property]).
I might think that even all offerings (i.e., individual peace-offerings) were subject to priestly gifts, and that this followed a fortiori, viz.: If chullin (non-consecrated animals), which are not subject to (the giving to the Cohein of) breast and thigh, are subject to priestly gifts (of chullin), then consecrated animals, which are subject to breast and thigh, how much more so should they be subject to priestly gifts! It is, therefore, written (Vayikra 7:34) "and I have given them (breast and thigh) to Aaron the Cohein." Nothing in addition to what is stated herein. I might think that chullin, too, are subject to (the giving to the Cohein of) breast and thigh, and that it follows a fortiori, viz.: If consecrated animals, which are not subject to priestly gifts (shoulder, cheeks, and maw), are subject to breast and thigh, then chullin, which are subject to priestly gifts, how much more so should they be subject to breast and thigh! It is, therefore, written "And this (shoulder, cheeks, and maw) shall be the judgment of the Cohanim."
"from the slaughterers of the slaughtering": The time of the slaughtering is the criterion. From here they ruled: If a stranger converted and he had a cow — If it were slaughtered before he converted, he is exempt (from priestly gifts); if after he converted, he is liable. If the matter is in doubt (safek), he is exempt, and "the burden of the proof is upon him who would remove (the object) from his neighbor's domain.
"whether ox or sheep": to include (in the obligation of priestly gifts) kilayim (hybrids). "whether ox or sheep": (Priestly gifts obtain) both in Eretz Yisrael and outside of it. (Now why is a verse needed to tell us this?) Does it not follow a fortiori, viz.: There is liability here (for priestly gifts), and there is liability for the first of the shearing. Just as the first of the shearing obtains in Eretz Yisrael and outside of it, so, the priestly gifts! Or, go in this direction: There is liability here (for priestly gifts), and there is liability for terumath reishith (i.e., terumah gedolah, which goes to the Cohein). Just as terumath reishith obtains only in Eretz Yisrael, so, the priestly gifts!
Let us see what it (priestly gifts) is most like. We derive something (i.e., priestly gifts) that is not land-linked and not consecrated, from something (the first of the shearing) which is not land-linked and not consecrated. And this is not to be refuted by terumath reishith, which is land-linked and consecrated.
Or, go in this direction: We derive something (priestly gifts), which obtains both with much and with little (produce), from something (terumath reishith), which obtains both with much and with little. And this is not to be refuted by the first shearing, which obtains only with many (and not with one sheep).
R. Yehudah says: The expounders of metaphors were wont to say: He (the Cohein) is given the shoulder for the hand (of Pinchas the Cohein), viz. (Bamidbar 25:7) "and he arose from the mist of the congregation and he (Pinchas) took a spear in his hand." "the cheeks": for the prayer (of Pinchas), viz. (Psalms 106:30) "and Pinchas arose and prayed." "the maw (kevah)": for (Bamidbar 25:8) "and (he pierced) the woman through her belly (kavathah)."
(דברים יח ג) וְזֶה יִהְיֶה מִשְׁפַּט הַכֹּהֲנִים – מְלַמֵּד שֶׁהַמַּתָּנוֹת יוֹצְאוֹת בְּדַיָּנִים.
(Devarim 18:3) "And this shall be the judgment of the Cohanim": We are hereby taught that the priestly gifts (shoulder, cheeks, and maw) are "law" (to the end of extracting them by court order from a thief who stole them from a Cohein who had acquired them from hefker [ownerless property]).
יָכוֹל אַף קָדָשִׁים יִהְיוּ חַיָּבִים בְּמַתָּנוֹת? וְדִין הוּא: וּמָה חֻלִּין, שֶׁאֵין חַיָּבִים בְּחָזֶה וָשׁוֹק, חַיָּבִים בַּמַּתָּנוֹת – קָדָשִׁים, שֶׁחַיָּבִים בְּחָזֶה וָשׁוֹק, אֵינוֹ דִין שֶׁיְּהוּ חַיָּבִים בַּמַּתָּנוֹת? תַּלְמוּד לוֹמַר: וְזֶה יִהְיֶה מִשְׁפַּט הַכֹּהֲנִים.
I might think that even all offerings (i.e., individual peace-offerings) were subject to priestly gifts, and that this followed a fortiori, viz.: If chullin (non-consecrated animals), which are not subject to (the giving to the Cohein of) breast and thigh, are subject to priestly gifts (of chullin), then consecrated animals, which are subject to breast and thigh, how much more so should they be subject to priestly gifts! It is, therefore, written (Vayikra 7:34) "and I have given them (breast and thigh) to Aaron the Cohein." Nothing in addition to what is stated herein. I might think that chullin, too, are subject to (the giving to the Cohein of) breast and thigh, and that it follows a fortiori, viz.: If consecrated animals, which are not subject to priestly gifts (shoulder, cheeks, and maw), are subject to breast and thigh, then chullin, which are subject to priestly gifts, how much more so should they be subject to breast and thigh! It is, therefore, written "And this (shoulder, cheeks, and maw) shall be the judgment of the Cohanim."
מֵאֵת הָעָם – וְלֹא מֵאֵת אֲחֵרִים. מֵאֵת הָעָם – וְלֹא מֵאֵת הַכֹּהֲנִים.
"from the people": and not from others (i.e., gentiles), and not from his fellow Cohanim.
מֵאֵת זֹבְחֵי הַזֶּבַח – פְּרָט לַטְּרֵפָה.
"from the slaughterers of the slaughtering": to exclude (from priestly gifts) a treifah (an organically defective animal).
מֵאֵת זֹבְחֵי הַזֶּבַח – אֵין לוֹ בּוֹ אֶלָּא בִּשְׁעַת זְבִיחָה בִּלְבַד. מִכָּן אָמְרוּ (חולין פ״י מ״ד): גֵּר שֶׁנִּתְגַּיֵּר וְהָיְתָה לוֹ פָּרָה, נִשְׁחֲטָה עַד שֶׁלֹּא נִתְגַּיֵּר – פָּטוּר; מִשֶּׁנִּתְגַּיֵּר – חַיָּב. סָפֵק – פָּטוּר, הַמּוֹצִיא מֵחֲבֵרוֹ עָלָיו הָרְאָיָה.
"from the slaughterers of the slaughtering": The time of the slaughtering is the criterion. From here they ruled: If a stranger converted and he had a cow — If it were slaughtered before he converted, he is exempt (from priestly gifts); if after he converted, he is liable. If the matter is in doubt (safek), he is exempt, and "the burden of the proof is upon him who would remove (the object) from his neighbor's domain.
אִם שׁוֹר אִם שֶׂה – לְרַבּוֹת כִּלְאַיִם, אִם שׁוֹר אִם שֶׂה – בֵּין בָּאָרֶץ בֵּין בְּחוּצָה לָאָרֶץ. וַהֲלֹא דִין הוּא: חִיֵּיב כָּאן וְחִיֵּיב בְּרֵאשִׁית הַגֵּז; מַה מָּצִינוּ בְּרֵאשִׁית הַגֵּז, נוֹהֵג בָּאָרֶץ וּבְחוּצָה לָאָרֶץ – אַף מַתָּנוֹת נוֹהֲגוֹת בָּאָרֶץ וּבְחוּצָה לָאָרֶץ! אוֹ כַּלֵּךְ לְדֶרֶךְ זוֹ: חִיֵּיב כָּאן וְחִיֵּיב בִּתְרוּמַת רֵאשִׁית; מַה תְּרוּמַת רֵאשִׁית, אֵינוֹ חַיָּב אֶלָּא בָּאָרֶץ – אַף מַתָּנוֹת אֵינָן נוֹהֲגוֹת אֶלָּא בָּאָרֶץ!
"whether ox or sheep": to include (in the obligation of priestly gifts) kilayim (hybrids). "whether ox or sheep": (Priestly gifts obtain) both in Eretz Yisrael and outside of it. (Now why is a verse needed to tell us this?) Does it not follow a fortiori, viz.: There is liability here (for priestly gifts), and there is liability for the first of the shearing. Just as the first of the shearing obtains in Eretz Yisrael and outside of it, so, the priestly gifts! Or, go in this direction: There is liability here (for priestly gifts), and there is liability for terumath reishith (i.e., terumah gedolah, which goes to the Cohein). Just as terumath reishith obtains only in Eretz Yisrael, so, the priestly gifts!
נִרְאֶה לְמִי דוֹמֶה? דָּנִים דָּבָר שֶׁאֵין תָּלוּי בָּאָרֶץ וּבַקֹּדֶשׁ מִדָּבָר שֶׁאֵין תָּלוּי בָּאָרֶץ וּבַקֹּדֶשׁ, וְאַל תּוֹכִיחַ תְּרוּמַת רֵאשִׁית, שֶׁהִיא תְּלוּיָה בָּאָרֶץ וּבַקֹּדֶשׁ.
Let us see what it (priestly gifts) is most like. We derive something (i.e., priestly gifts) that is not land-linked and not consecrated, from something (the first of the shearing) which is not land-linked and not consecrated. And this is not to be refuted by terumath reishith, which is land-linked and consecrated.
אוֹ כַּלֵּךְ לְדֶרֶךְ זוֹ: דָּנִים דָּבָר שֶׁנּוֹהֵג בֵּין בַּמְרֻבֶּה בֵּין בַּמּוּעָט מִדָּבָר שֶׁנּוֹהֵג בַּמְרֻבֶּה וּבַמּוּעָט, וְאַל יוֹכִיחַ רֵאשִׁית הַגֵּז, שֶׁאֵינוֹ נוֹהֵג אֶלָּא בַּמְרֻבֶּה.
Or, go in this direction: We derive something (priestly gifts), which obtains both with much and with little (produce), from something (terumath reishith), which obtains both with much and with little. And this is not to be refuted by the first shearing, which obtains only with many (and not with one sheep).
תַּלְמוּד לוֹמַר: אִם שׁוֹר אִם שֶׂה, בֵּין בָּאָרֶץ בֵּין בְּחוּצָה לָאָרֶץ.
It is, therefore, written "whether ox or sheep": both in Eretz Yisrael or outside it.
וְנָתַן לַכֹּהֵן – לַכֹּהֵן עַצְמוֹ.
"and he shall give to the Cohein": to the Cohein himself.
הַזְּרוֹעַ – זְרוֹעַ שֶׁל יָמִין.
"the shoulder": the right shoulder.
וְהַלְּחָיַיִם – זֶה לְחִי הַתַּחְתּוֹן.
"the cheeks": the upper and the lower cheeks.
וְהַקֵּבָה – כְּמַשְׁמָעָהּ.
"and the maw": as implied.
רַבִּי יְהוּדָה אוֹמֵר, דּוֹרְשֵׁי רְשׁוּמוֹת אוֹמְרִים: נָתַן לוֹ זְרוֹעַ תַּחַת הַיָּד, וְכֵן הוּא אוֹמֵר (במדבר כה ז): ״וַיָּקָם מִתּוֹךְ הָעֵדָה וַיִּקַּח רֹמַח בְּיָדוֹ״; וְהַלְּחָיַיִם תַּחַת תְּפִלָּה, וְכֵן הוּא אוֹמֵר (תהלים קו ל) ״וַיַּעֲמֹד פִּינְחָס וַיְפַלֵּל״; הַקֵּבָה תַּחַת קֵיבָה, שֶׁנֶּאֱמַר (במדבר כה ח): ״וְאֶל הָאִשָּׁה אֶל קֳבָתָהּ״!
R. Yehudah says: The expounders of metaphors were wont to say: He (the Cohein) is given the shoulder for the hand (of Pinchas the Cohein), viz. (Bamidbar 25:7) "and he arose from the mist of the congregation and he (Pinchas) took a spear in his hand." "the cheeks": for the prayer (of Pinchas), viz. (Psalms 106:30) "and Pinchas arose and prayed." "the maw (kevah)": for (Bamidbar 25:8) "and (he pierced) the woman through her belly (kavathah)."