Under hopeless circumstances he hopefully believed (Romans 4:18). (Weymouth)
Abraham's faith seemed to be in a thorough correspondence with the power and constant faithfulness of Jehovah. In the outward circumstances in which he was placed, he had not the greatest cause to expect the fulfillment of the promise. Yet he believed the Word of the Lord, and looked forward to the time when his seed should be as the stars of heaven for multitude.
O my soul, thou hast not one single promise only, like Abraham, but a thousand promises, and many patterns of faithful believers before thee: it behooves thee, therefore, to rely with confidence upon the Word of God. And though He delayeth His help, and the evil seemeth to grow worse and worse, be not weak, but rather strong, and rejoice, since the most glorious promises of God are generally fulfilled in such a wondrous manner that He steps forth to save us at a time when there is the least appearance of it.
He commonly brings His help in our greatest extremity, that His finger may plainly appear in our deliverance. And this method He chooses that we may not trust upon anything that we see or feel, as we are always apt to do, but only upon His bare Word, which we may depend upon in every state.
--C. H. Von Bogatzky
Remember it is the very time for faith to work when sight ceases. The greater the difficulties, the easier for faith; as long as there remain certain natural prospects, faith does not get on even as easily as where natural prospects fail.