Genesis 15:6

And he believed in the LORD; and he counted it to him for righteousness.

Ver 6. And he believed.] When thus the promise was repeated. So needful it is, that the word should be often preached, and the sweet promises of the gospel beaten to the smell; that God's "name being as an ointment poured out, the virgins may love him," Son 1:3 believe in him, and "rejoice with joy unspeakable, and full of glory." 1Pe 1:8

And he counted it to him for righteousness.] This imputative righteousness the Papists scoff at, calling it putative, or imaginary. This the Jews also jeer at to this day; as their fathers did of old, Rom 10:2-3 so do they. For being asked whether they believe to be saved by the righteousness of Christ imputed to them, they answer, that every fox must pay his own skin to the finger. But is not Christ called in their law, "Jehovah our righteousness?" Jer 23:6 And how so, but by means of that imputation so often hammered on by the apostle? Rom 4:1-25 adding after all, that what is said here of Abram, "is not written for his sake alone, that it was imputed to him, but for us also, to whom it shall be imputed, if we believe on him that raised up Jesus," &c. Rom 4:24 If Adam's sin be mine, though I committed it not; why should it seem so strange, that the merit of Christ's entire obedience should by the like means be mine, though I wrought it not? See Rom 5:19 2 Corinthians 5:19. "If he hath wronged thee aught, reckon that to me," said Paul to Philemon, concerning Onesimus; Phm 1:18 saith Christ to his Father concerning us. And - to stop the Papists' mouth - if another man's faith may benefit infants at their baptism, as Bellarmine affirmeth; why should it seem so absurd that believers should be benefited by Christ's righteousness imputed?