Matthew 17:21

Then came the disciples to Jesus apart, and said, Why could not we cast him out?

And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you.

And while they abode in Galilee, Jesus said unto them, The Son of man shall be betrayed into the hands of men:

And they shall kill him, and the third day he shall be raised again. And they were exceeding sorry.