Matthew 16:8

Being not weak in faith, [Abraham] considered not his own body now dead, when he was about an hundred years old, neither yet the deadness of Sarah's womb; he staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God.

Is it easier to say to the sick of the palsy, Thy sins be forgiven thee or to say, Arise, and take up thy bed, and walk?—If thou canst believe, all things are possible to him that believeth.