2 Kings 19:1
And it came to pass, when king Hezekiah heard it, that he rent his clothes, and covered himself with sackcloth, and went into the house of the LORD. And it came to pass, when king Hezekiah heard it, that he rent his clothes, and covered himself with sackcloth, and went into the house of the LORD.
What Hezekiah heard was the Assyrian challenge against God, spoken in open defiance of Heaven. It was specifically the reproach of the living God uttered by Rabshakeh at the close of the conference. On hearing it he grieved deeply and humbled himself in mourning. He rent his garments and covered himself with sackcloth, then went into the house of the Lord to worship.
From that place of worship he sent a messenger to Isaiah, declaring the day to be a day of trouble and of rebuke and of blasphemy. He expressed hope that the Lord would hear all the words of Rabshakeh and reprove them. He asked Isaiah to lift up prayer for the remnant that were left. Hezekiah himself joined Isaiah in praying and crying to Heaven. God answered the prayers of His servants with the message not to fear the Assyrian blasphemy, for He would send a blast upon Sennacherib, turn him back to his own land, and cause him to fall by the sword there.