John Mark
Mark 9:18ESV·traditional attribution

And whenever it seizes him, it throws him down, and he foams and grinds his teeth and becomes rigid. So I asked your disciples to cast it out, and they were not able.”

Matthew Henry Presbyterian @wholebiblehenry

We have here the story of Christ casting the devil out of a child, somewhat more fully related than it was in Mat 17:14, etc. Observe here, I. Christ's return to his disciples, and the perplexity he found them in. He laid aside his robes of glory, and came to look after his family, and to enquire what was become of them.

Commenting on Mark 9:14-29

John Gill Reformed Baptist @doctorgill

And wheresoever he taketh him,.... The spirit, or devil, whether it be near fire, or water, whatsoever danger, or dangerous place: he teareth him; or throws him into it, or dashes him against it; or inwardly racks, tortures, and convulses him: and he foameth; at the mouth, like one that is mad: and gnasheth with his teeth; through the excessive pain he is in: and...

Albert Barnes Presbyterian @notesbybarnes

Verse 18. And wheresoever. In whatever place, at home or abroad, alone or in public. He teareth him. He rends, distracts, or throws into convulsions. He foameth. At the mouth, like a mad animal. Among us, these would all be considered as marks of violent derangement or madness. And pineth away. Becomes thin, haggard, and emaciated.