Romans 4:19-22

19Without being weak in faith, he considered his own body as dead (because he was about one hundred years old) and the deadness of Sarah’s womb.

20He did not waver in unbelief about the promise of God but was strengthened in faith, giving glory to God.

21He was fully convinced that what God promised he was also able to do.

22So indeed it was credited to Abraham as righteousness.