John Gill Commentary Deuteronomy 4:24

"For Jehovah thy God is a devouring fire, a jealous God." — Deuteronomy 4:24 (ASV)

For the Lord your God is a consuming fire
To his enemies; his wrath is like fire to burn up and destroy all that oppose him and break his commands, and especially idolaters; whose sin of all others is the most provoking to him, since it strikes at his being, his honour and glory; wherefore it follows,

even a jealous God ;
who is jealous of his honour in matters of worship, and will not suffer his glory to be given to another, nor his praise to graven images, without resenting it or punishing for it.