Romans 4:18-21

[For Abraham, human reason for] hope being gone, hoped in faith that he should become the father of many nations, as he had been promised, So [numberless] shall your descendants be. [Gen. 15:5.] He did not weaken in faith when he considered the [utter] impotence of his own body, which was as good as dead because he was about a hundred years old, or [when he considered] the barrenness of Sarah's [deadened] womb. [Gen. 17:17; 18:11.] No unbelief or distrust made him waver (doubtingly question) concerning the promise of God, but he grew strong and was empowered by faith as he gave praise and glory to God, Fully satisfied and assured that God was able and mighty to keep His word and to do what He had promised.