John Calvin on Genesis 17:3

3. And Abram fell on his face We know that this was the ancient rite of adoration. Moreover, Abram testifies, first, that he acknowledges God, in whose presence all flesh ought to keep silence, and to be humbled; and, secondly that he reverently receives and cordially embraces whatever God is about to speak. If, however, this was intended as a confession of faith, we must observe, that the faith which relies upon the grace of God cannot be disjoined from a pure conscience. God, in offering his grace to Abram, requires of him a sincere disposition to live justly and homily. Abram, in prostrating himself, declares that he obediently receives both. That is, both the promise of grace, and the command to yield obedience. — Ed. Let us therefore remember, that in one and the same bond of faith, the gratuitous adoption in which our salvation is placed, is to be combined with newness of life. And although Abram utters not a word, he declares more fully by his silence, than if he had spoken with a loud and sounding voice, that he yields obedience to the word of God.