וְהִתְבָּרֲכ֣וּ בְזַרְעֲךָ֔ כֹּ֖ל גּוֹיֵ֣י הָאָ֑רֶץ עֵ֕קֶב אֲשֶׁ֥ר שָׁמַ֖עְתָּ בְּקֹלִֽי׃
און בענטשן װעלן זיך מיט דײַן זאָמען אַלע פֿעלקער פֿון דער ערד, דערפֿאַר װאָס דו האָסט צוגעהערט צו מײַן קול.
Rashi
את ברכת אברהם THE BLESSING OF ABRAHAM, (i. e. the blessing which He gave to (Abraham) to whom He promised, (12:2) “and I will make of thee a great nation”, and (26:4) “and all the nations shall bless themselves by thy seed”: may these blessings have been said regarding you — may that great nation and that blessed seed issue from you.
Chizkuni
עקב אשר שמע אברהם בקולי, “as a consequence of Avraham having listened to My voice;” a reference to the binding of Yitzchok. The same formulation occurs also in Genesis 22,18: עקב אשר שמעת בקולי, “(G-d to Avraham) “as a consequence of your having listened to My voice.”
Rashbam
בקולי , a reference to the binding of Yitzchok where the Torah had used the expression (22,18) עקב אשר שמעת בקולי, “as a consequence of your heeding My instructions.