John Calvin Commentary Isaiah 10:16

"Therefore will the Lord, Jehovah of hosts, send among his fat ones leanness; and under his glory there shall be kindled a burning like the burning of fire." — Isaiah 10:16 (ASV)

Therefore shall the Lord, the Lord of hosts, send among his fat ones leanness. He continues with the previous doctrine, declaring that the Lord will show the Assyrian how undeservedly he exalts himself and will throw down his arrogance, in which he foolishly delights.

Since he trusted in his wealth and his forces, Isaiah declares that the Lord will take them away. He does this using the metaphor of fatness and leanness. By the word fatness, he means both riches and military power, in which he placed too much confidence; it is as if he had said, “Everything fat and rich that he possesses, the Lord will make all of it lean.”

It is not uncommon to compare prosperity to fatness; for just as horses that are too fat become refractory, so that they throw the rider or kick when anyone comes near them, so among people, abundance produces a fierce disposition, which is subdued by leanness.

And under his glory he shall kindle a burning. There is great beauty in the comparison that a fire will be laid under his glory; for it means that the greater the splendor of his prosperity, the more abundant the fuel for the conflagration will be.

Yet it also shows that he will be utterly reduced to nothing, as if one were to cut down a tree from the roots or overturn a house from its foundation.

If only the branches of a tree are cut down, it quickly sprouts again; or if the roof of a house is consumed by fire, its other parts remain uninjured. He therefore leaves him nothing but asserts that he will be brought down by utter destruction.

As the burning of a fire. The particle as, which indicates the comparison, does not mean that the language is metaphorical, but rather that the burning will be such that it utterly consumes the glory of the Assyrian.