Mark 9:18
Whenever it seizes him, it throws him down. He foams at the mouth, gnashes his teeth and becomes rigid. I asked your disciples to drive out the spirit, but they could not — the clinical description of the possession (throws down, foams, gnashes, becomes rigid) describes what appears to be a severe seizure disorder, though the Gospel attributes it to a spiritual cause. I asked your disciples but they could not: the failure is public, complete, and contrasted with the success they had on their earlier mission (Mark 6:13). Something has gone wrong.