John Calvin Commentary Isaiah 37:9

"And he heard say concerning Tirhakah king of Ethiopia, He is come out to fight against thee. And when he heard it, he sent messengers to Hezekiah, saying," — Isaiah 37:9 (ASV)

And hearing concerning Tirhakah king of Ethiopia. From what follows we can conjecture the reason why the king of Assyria suddenly departed from Judea. The kings of Egypt and Ethiopia had formed a league with each other against Sennacherib because they saw that his power was becoming excessive and that his invasion of other countries had no limit. Therefore, they readily concluded that unless they opposed his violence early on, they also would be in imminent danger from him.

These kings did not intend to provide for the safety of Judea at their own loss but looked to themselves, for such great power possessed by one individual is commonly and deservedly viewed with suspicion by other princes and nations. They therefore acted wisely in joining their forces and meeting him early, for separately they would easily have been subdued and destroyed. For this reason, these two kings took up arms together to repel the power and violence of that tyrant.

He sent messengers to Hezekiah. The king of Assyria, being involved in such a hazardous war, sends messengers to Hezekiah to induce him by terrors and threats to surrender. For tyrants are maddened by ambition and by a false opinion of their own greatness, and therefore imagine that their words, the report of their name, and even their shadow, will strike terror into all people.

Entangled in a hazardous war, he thinks of subduing Judea, from which he had been compelled to withdraw. He was ashamed of not having continued the siege, but perhaps thought that he would gain in his absence what he could not accomplish by his presence.

But the Lord miraculously assisted His people, who appeared to be very near destruction. And, first, to restrain the violence of this tyrant, He presented hindrances and obstructions from which the tyrant could not so quickly extricate himself—just as if one should lay a bridle on the mouth or a hook on the nose of a wild and savage beast, as the Prophet will afterwards say (Isaiah 37:29). His rage and cruelty, indeed, are not abated but are restrained so that they can do no harm.

We see the same thing in the present day. How many cruel tyrants would wish that the Church of God were destroyed! What schemes are employed to accomplish it! How diversified are the plans they form! What forces do they assemble from every quarter! But when they think they will accomplish anything, the Lord suddenly raises up enemies against them, sometimes even brings them to fight with each other, and turns against themselves that cruelty which they wished to exercise against the children of God.

Yet they go on in their cruelty and do not cease to attempt this or that.

So this Sennacherib, though surrounded by difficulties, does not cease to annoy Hezekiah. He addresses him from his royal throne as if Hezekiah were a despicable slave and commands him as if he were his vassal. He even addresses God Himself with insolent and abusive language, and goes beyond his agent Rabshakeh in arrogance. For, although Rabshakeh’s words had the same meaning, still this man, in a more impudent manner and, as we may say, with a more open mouth, reviles God.