John Calvin Commentary Romans 4:22

"Wherefore also it was reckoned unto him for righteousness." — Romans 4:22 (ASV)

And it was therefore imputed, etc. It now becomes more clear how and in what manner faith brought righteousness to Abraham; and that was because he, leaning on God’s word, did not reject the promised favor. And this connection of faith with the word ought to be well understood and carefully remembered; for faith can bring us nothing more than what it receives from the word. Therefore, he does not become immediately just who is imbued only with a general and confused idea that God is true, unless he relies on the promise of his favor.