Matthew 17:15

Lord, have mercy - The word “Lord” here means “Sir,” a title of civility, not implying divinity.

My son - This was an only son (Luke). He was possessed with a devil. This calamity was attended with the following symptoms: he was lunatic (see the notes at Matthew 4:24); he was sore vexed; that is, he suffered greatly, or was greatly afflicted; he fell often suddenly, in the manner of persons having epileptic fits; he was dumb - that is, he was mute except when the seizure was coming upon him, for Luke says that when the spirit took him he cried suddenly out; he foamed and gnashed with his teeth, and wasted away, or became poor and emaciated. Luke Luke 9:39 adds of the evil spirit, “it teareth him that he foameth again, and, bruising him, hardly departeth from him;” that is, scarcely departed from him, or he had only short intervals of reason, for so the passage in Luke, “bruising him, hardly departeth from him,” should be translated.