Another interpretation: "of the dew of heaven" - this is Scripture; "and of the fat places of the earth" - this is Mishnah; "and plenty of grain" - this is Talmud; "and wine" - this is Aggadah. "Let peoples serve you" - these are the seventy nations. "And nations [le'umim] bow down to you" - these are the children of Ishmael and the children of Keturah, as it is written, "And the sons of Dedan were Asshurim and Letushim and Leummim" (Genesis 25:3). "Be lord over your brothers" - this is Esau and his chiefs. "And let your mother's sons bow down to you" - here it says "your mother's sons," but elsewhere it says "your father's sons" (Genesis 49:8). Rather, because Jacob married four wives he said "your father's sons," while Isaac, who married only one, said "your mother's sons." "Cursed be those who curse you, and blessed be those who bless you" - but elsewhere it says "blessed be those who bless you, and cursed be those who curse you" (Numbers 24:9). Rather, because Balaam was a hater, he opened with blessing and closed with cursing.
Isaac's Blessing Read as Scripture Mishnah Talmud and Aggadah
Yalkut Shimoni on Torah 115:17
דָּבָר אַחֵר מִטַּל הַשָּׁמַיִם זֶה מִקְרָא וּמִשְׁמַנֵּי הָאָרֶץ, זֶה מִשְׁנָה וְרֹב דָּגָן, זֶה תַּלְמוּד וְתִירֹשׁ, זֶה אַגָּדָה. יַעַבְדוּךָ עַמִּים, אֵלּוּ שִׁבְעִים אוּמוֹת. וְיִשְׁתַּחֲווּ לְךָ לְאֻמִּים, אֵלּוּ בְּנֵי יִשְׁמָעֵאל וּבְנֵי קְטוּרָה, דִּכְתִיב (בראשית כה, ג) "וּבְנֵי דְּדָן הָיוּ אַשּׁוּרִם וּלְטוּשִׁם וּלְאֻמִּים". הֱוֵה גְּבִיר לְאַחֶיךָ זֶה עֵשָׂו וְאַלוּפָיו. וְיִשְׁתַּחֲווּ לְךָ בְּנֵי אִמֶּךָ, הָכָא אַתְּ אָמַרְתְּ בְּנֵי אִמֶּךָ, וּלְהַלָּן הוּא אוֹמֵר "בְּנֵי אָבִיךָ", אֶלָּא יַעֲקֹב עַל יְדֵי שֶׁנָּשָׂא אַרְבַּע נָשִׁים הוּא אוֹמֵר "בְּנֵי אָבִיךָ", יִצְחָק שֶׁלֹּא נָשָׂא אֶלָּא אַחַת הוּא אוֹמֵר בְּנֵי אִמֶּךָ. אֹרֲרֶיךָ אָרוּר וּמְבָרֲכֶיךָ בָּרוּךְ, וּלְהַלָּן הוּא אוֹמֵר (במדבר כד, ט) "מְבָרֲכֶיךָ בָרוּךְ וְאֹרֲרֶיךָ אָרוּר" אֶלָּא בִּלְעָם עַל יְדֵי שֶׁהָיָה שׂוֹנֵא, פּוֹתֵחַ בִּבְרָכָה וְחוֹתֵם בִּקְלָלָה.