Sforno on Genesis 22:18/ספורנו על בראשית כ״ב:י״ח

1והתברכו בזרעך כל גויי הארץ, if and when your descendants will join together in proclaiming the holy name of the Lord, the nations of the world will be blessed as they will try to follow your example and to be like you.

2עקב אשר שמעת בקולי, as a consequence. This is what we know as the concept of שכר מצוה מצוה, that the fulfillment of one commandment begets the opportunity of fulfilling another commandment. By doing this you will receive the satisfaction that your children will be a banner to the nations, teachers to the gentile nations instructing them in how to serve the Lord. All of this will accrue to you as a credit, a merit.