Romans 4:20-22
[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.
[22]And therefore it was imputed to him for righteousness.

Hebrews 10:22-23
[22]Let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water.
[23]Let us hold fast the profession of our faith without wavering; (for he is faithful that promised;)