Genesis 27:29

בני אמך THY MOTHER’S SONS — Jacob, however, said to Judah (49:8) “Thy father’s sons (shall bow down to thee]”, because he had sons by several wives, but here, because he (Isaac) had but one wife he said “thy mother’s sons” (Genesis Rabbah 66:4). ארריך ארור ומברכיך ברוך THEY THAT CURSE THEE SHALL BE CURSED AND THEY THAT BLESS THEE SHALL BE BLESSED — But in the case of Balaam Scripture says (Numbers 24:9) “Blessed be everyone that blesseth thee and cursed be every one that curseth thee”. The explanation is: the righteous have sufferings first and happiness afterwards, so that in point of time those who curse and afflict them (cause them suffering) come before those who bless them (cause them happiness) — therefore Isaac, a righteous man, invokes a curse upon those who themselves curse before he invokes a blessing upon those who bless. The wicked however have happiness first and suffering afterwards; therefore Balaam, a wicked man, invokes the blessing before the curse (Genesis Rabbah 66:4).

יַֽעַבְד֣וּךָ עַמִּ֗ים (וישתחו) [וְיִֽשְׁתַּחֲו֤וּ] לְךָ֙ לְאֻמִּ֔ים הֱוֵ֤ה גְבִיר֙ לְאַחֶ֔יךָ וְיִשְׁתַּחֲו֥וּ לְךָ֖ בְּנֵ֣י אִמֶּ֑ךָ אֹרְרֶ֣יךָ אָר֔וּר וּֽמְבָרְכֶ֖יךָ בָּרֽוּךְ׃

let peoples serve thee, and nations bow down to thee: be lord over thy brethren, and let thy mother’s sons bow down to thee: cursed be those that curse thee, and blessed be those that bless thee.