Genesis 15:6

Accordingly let us learn, I beseech you, a lesson for ourselves as well from the patriarch: Let us believe in the words of God and trust in his promise. Let us not apply the yardstick of our own reasoning but give evidence of deep gratitude. This, you see, will succeed in making us also be seen to be righteous and will quickly cause us to attain to the promise made by him. In Abraham's case, however, the promise was made that a complete multitude would develop from his descendants. The effect of the promise was beyond the limits of nature and human logic. Hence faith in God won righteousness for him. In our case, … if we are alert enough to see it, he promised much more. We are able in great measure to transcend human reasoning, provided we believe in the power of the One who promises, in order that we may gain also righteousness from faith and attain to the good things promised.

Abraham, styled "the friend," [Isaiah 41:8] was found faithful, inasmuch as he rendered obedience to the words of God. He, in the exercise of obedience, went out from his own country, and from his kindred, and from his father's house, in order that, by forsaking a small territory, and a weak family, and an insignificant house, he might inherit the promises of God. For God said to him, "Get you out from your country, and from your kindred, and from your father's house, into the land which I shall show you. And I will make you a great nation, and will bless you, and make your name great, and you shall be blessed. And I will bless them that bless you, and curse them that curse you; and in you shall all the families of the earth be blessed." [Genesis 12:1-3] And again, on his departing from Lot, God said to him, "Lift up your eyes, and look from the place where you now are, northward, and southward, and eastward, and westward; for all the land which you see, to you will I give it, and to your seed forever. And I will make your seed as the dust of the earth, [so that] if a man can number the dust of the earth, then shall your seed also be numbered." [Genesis 13:14-16] And again [the Scripture] says, "God brought forth Abram, and spoke unto him, Look up now to heaven, and count the stars if you are able to number them; so shall your seed be. And Abram believed God, and it was counted to him for righteousness." [Genesis 15:5-6] On account of his faith and hospitality, a son was given him in his old age; and in the exercise of obedience, he offered him as a sacrifice to God on one of the mountains which He showed him.

He believed God, and it was reckoned to him as righteousness. The Apostle recalls this sentence (Rom. IV, 3) to commend the grace of God, lest circumcision should boast, and the uncircumcised nations should be unwilling to admit to the faith of Christ: for this …

Note, A fiducial practical acceptance of, and dependence upon, God's promise of grace and glory, in and through Christ, is that which, according to the tenour of the new covenant, gives us a right to all the blessings contained in that promise. All believers are justified as Abram was, and it was his faith that was counted to him for righteousness.

Note, Those who would have the comfort of the promises must mix faith with the promises. See how the apostle magnifies this faith of Abram, and makes it a standing example, Rom. iv. He was not weak in faith; he staggered not at the promise; he was strong in faith; he was fully persuaded.