"And the holy garments of Aaron shall be for his sons after him, to be anointed in them" (Exodus 29:28-36). Rav Chisda said: the priestly gifts may be eaten only roasted, and only with mustard. What is the reason? "Le-moshcha" [for anointing] is read as "for greatness," in the manner that kings eat. "And it shall belong to Aaron and to his sons" (Leviticus 24:9). Our Rabbis taught: how does a High Priest offer a portion as the foremost? He says, "this burnt offering I am offering, this meal offering I am offering." How does he take a portion as the foremost? He says, "this sin offering I am offering," and he eats it; and he takes one loaf of the two loaves, and four or five of the showbread. Rabbi says: always five, as it is said, "and it shall belong to Aaron and to his sons," half to Aaron and half to his sons.
The Priestly Gifts Are Eaten the Way Kings Eat
Yalkut Shimoni on Torah 384:3
(שמות כט כח-לו) וּבִגְדֵי הַקֹּדֶשׁ אֲשֶׁר לְאַהֲרֹן יִהְיוּ לְבָנָיו אַחֲרָיו לְמָשְׁחָה בָהֶם. אֲמַר רַב חִסְדָּא, מַתְּנוֹת כְּהֻנָּה אֵין נֶאֱכָלִין אֶלָּא צָלִי, וְאֵין נֶאֱכָלִין אֶלָּא בְּחַרְדָּל, מַאי טַעְמָא, לְמָשְׁחָה, לִגְדֻלָּה, כְּדֶרֶךְ שֶׁהַמְּלָכִים אוֹכְלִים. (ויקרא כד, ט) וְהָיְתָה לְאַהֲרֹן וּלְבָנָיו. תָּנוּ רַבָּנָן. כֹּהֵן גָּדוֹל כֵּיצַד מַקְרִיב חֵלֶק בָּרֹאשׁ, אוֹמֵר, עוֹלָה זוֹ אֲנִי מַקְרִיב, מִנְחָה זוֹ אֲנִי מַקְרִיב. כֵּיצַד נוֹטֵל חֵלֶק בָּרֹאשׁ, אוֹמֵר חַטָּאת זוֹ אֲנִי מַקְרִיב, וְאוֹכֵל, וְנוֹטֵל חַלָּה אַחַת מִשְּׁתֵּי חַלּוֹת, אַרְבַּע אוֹ חָמֵשׁ מִמַּעֲשֵׂה לֶחֶם הַפָּנִים. רַבִּי אוֹמֵר, לְעוֹלָם חָמֵשׁ, שֶׁנֶּאֱמַר "וְהָיְתָה לְאַהֲרֹן וּלְבָנָיו", מֶחֱצָה לְאַהֲרֹן וּמֶחֱצָה לְבָנָיו.