וְהִתְבָּרֲכ֣וּ בְזַרְעֲךָ֔ כֹּ֖ל גּוֹיֵ֣י הָאָ֑רֶץ עֵ֕קֶב אֲשֶׁ֥ר שָׁמַ֖עְתָּ בְּקֹלִֽי׃
Et toutes les nations de la terre s’estimeront heureuses par ta postérité, en récompense de ce que tu as obéi à ma voix."
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.