Hebrews 10:23

10:23 And let us hold unwaveringly to the hope that we confess, for the one who made the promise is trustworthy.

Romans 4:20-21

4:20 He did not waver in unbelief about the promise of God but was strengthened in faith, giving glory to God. 4:21 He was fully convinced that what God promised he was also able to do.