What does Isaiah 10:13 mean?

The Lord has said that once His work of judging His people through the Assyrians is finished, He will turn and punish the Assyrian king for his arrogance (Isaiah 10:12). Sargon II may be one of the kings described here, along with Sennacherib, though the attitude is representative of many of the kings of Assyria.

Isaiah puts words in the mouth of those kings to describe their arrogance. They genuinely believe in their greatness. They are convinced they have succeeded in destroying one nation after another by their own strength. They remove the boundaries between nations by claiming each one they overpower as their own. They have plundered the treasures of each new conquered people, adding to Assyria's enormous wealth. They are as unstoppable as a bull, bringing down everyone who dares to stand against Assyria's might.

The prophet Isaiah is not overstating the attitude of these rulers. These over-the-top descriptions of kings from this era of history can be found in ancient inscriptions. Each insisted on trumpeting his accomplishments and claiming ultimate power in the world. The Lord detested their blind pride. He knew they were merely tools in His hands. Tools that He would quickly dispose of once He was done with them.