אָמַר רַבִּי זְכַרְיָה מִשּׁוּם רַבִּי יִשְׁמָעֵאל: בִּיקֵּשׁ הַקָּדוֹשׁ
בָּרוּךְ הוּא לְהוֹצִיא כְּהוּנָּה מִשֵּׁם, שֶׁנֶּאֱמַר: ״וְהוּא כֹהֵן לְאֵל
עֶלְיוֹן״. כֵּיוָן שֶׁהִקְדִּים בִּרְכַּת אַבְרָהָם לְבִרְכַּת הַמָּקוֹם —
הוֹצִיאָהּ מֵאַבְרָהָם.
Rabbi Zekharya said in the
name of Rabbi Yishmael: The Holy One, Blessed be He, wanted the priesthood to
emerge from Shem, so that his children would be priests, as it is
stated: “And Melchizedek king of Salem brought forth bread and wine; and
he was priest of God the Most High” (Genesis 14:18). Once
Melchizedek, traditionally identified as Shem, placed the blessing of
Abraham before the blessing of the Omnipresent, He had the priesthood emerge
from Abraham in particular, and not from any other descendant of Shem.
שֶׁנֶּאֱמַר: ״וַיְבָרְכֵהוּ וַיֹּאמַר בָּרוּךְ אַבְרָם לְאֵל עֶלְיוֹן קֹנֵה
שָׁמַיִם וָאָרֶץ וּבָרוּךְ אֵל עֶלְיוֹן״. אָמַר לוֹ אַבְרָהָם: וְכִי
מַקְדִּימִין בִּרְכַּת עֶבֶד לְבִרְכַּת קוֹנוֹ? מִיָּד נְתָנָהּ לְאַבְרָהָם,
שֶׁנֶּאֱמַר: ״נְאֻם ה׳ לַאדֹנִי שֵׁב לִימִינִי עַד אָשִׁית אֹיְבֶיךָ הֲדֹם
לְרַגְלֶיךָ״, וּבָתְרֵיהּ כְּתִיב: ״נִשְׁבַּע ה׳ וְלֹא יִנָּחֵם אַתָּה כֹהֵן
לְעוֹלָם עַל דִּבְרָתִי מַלְכִּי צֶדֶק״. עַל דִּיבּוּרוֹ שֶׁל מַלְכִּי צֶדֶק.
As it is stated: “And he
blessed him and said: Blessed be Abram of God Most High, Maker of heaven and
earth, and blessed be God the Most High” (Genesis 14:19–20). Abraham
said to him: And does one place the blessing of the servant before the blessing
of his master? You should have blessed God first. Immediately the
Holy One, Blessed be He, gave the priesthood to Abraham, as it is
stated: “The Lord says to my lord: Sit at My right hand, until I make your
enemies your footstool” (Psalms 110:1), and afterward it is written:
“The Lord has sworn, and will not repent: you shall be a priest forever,
because you are a king of righteousness [al divrati malki tzedek]”
(Psalms 110:4), which is explained homiletically to mean: Due to the
improper words [divrati] of Melchizedek, the offspring of Abraham
shall be priests of God forever. (source)