Mark 9:19-24  NAS

And He answered them and said, "O unbelieving generation, how long shall I be with you?  How long shall I put up with you?  Bring him to Me!"  They brought the boy to Him.  When he saw Him, immediately the spirit threw him into a convulsion, and falling to the ground, he began rolling around and foaming at the mouth.  And He asked his father, "How long has this been happening to him?"  And he said, "From childhood.  It has often thrown him both into the fire and into the water to destroy him.  But if You can do anything, take pity on us and help us!"  And Jesus said to him, " 'If You can?' All things are possible to him who believes."  Immediately the boy's father cried out and said, "I do believe; help my unbelief."