Romans 4:19-21 KJV

[19] And being not weak in faith, he considered not his own body now dead, when he was about an hundred years old, neither yet the deadness of Sara's womb: [20] He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God; [21] And being fully persuaded that, what he had promised, he was able also to perform.