This event occurred in the period just after the decimation of the Assyrian army of Sennacherib. Sennacherib had fled to Nineveh and was afterwards assassinated by his sons. Additional information regarding this story is found in II Kings 20. Hezekiah’s illness occurred after that attempted invasion, and probably close to that time. Josephus affirms this when he says that the sickness occurred soon after the destruction of the army of Sennacherib. The Lord may have brought the illness upon him to prevent him from being prideful over the conquering of the Assyrian army. Hezekiah’s prayers caused the Lord to act against the Assyrians. Hezekiah must have been worn out as a result of the massive Assyrian victories in Israel and the 46 cities of Judah as well as the threats they made against Judah. Another cause of his anxiety was, that he had at that time no children, and consequently he had reason to believe that his kingdom would descend into a contentious struggle for the crown.
Now the sickness was severe enough to end unto death. And Isaiah bringing him God’s Word, said unto him that he shalt die, and not live. The manifestation of this illness was a boil (II Kings 20:7). Therefore, he should make the necessary disposition of his earthly possessions, other aspects and bequeathments in his will.
As it was announced and from all human appearance; the disease was deadly, and of which he could not recover through any human intervention. Only Almighty power could save him; and while this is true, it was God through the prophet Isaiah who was delivering to him the sentence of death.