Mark 9:19-21

19“You unbelieving generation,” Jesus replied, “how long shall I stay with you? How long shall I put up with you? Bring the boy to me.”

20So they brought him. When the spirit saw Jesus, it immediately threw the boy into a convulsion. He fell to the ground and rolled around, foaming at the mouth.

21Jesus asked the boy’s father, “How long has he been like this?” “From childhood,” he answered.