As they approached the crowd, a man came up to him and knelt before him. "Lord," he said, "take pity on my son, who is demented and in a serious condition. For example, he often falls into the fire and frequently into the water. I have brought him to your disciples but they could not cure him." In reply Jesus said: "What an unbelieving and perverse lot you are! How long must I remain with you? How long can I endure you? Bring him here to me!" Then Jesus reprimanded him, and the demon came out of him. That very moment the boy was cured.
The disciples approached Jesus at that point and asked him privately, "Why could we not expel it?" "Because you have so little trust," he told them. "I assure you, if you had faith the size of a mustard seed, you would be able to say to this mountain, 'Move from here to there,' and it would move. Nothing would be impossible for you. This kind does not leave but by prayer and fasting."
When they met again in Galilee, Jesus said to them, "The Son of Man is going to be delivered into the hands of men who will put him to death, and he will be raised up on the third day." At these words they were overwhelmed with grief.