2 Kings 19:2

he sent … to Esai R.V. Isaiah. The historian has up to this time never mentioned the name of the great prophet. But we know from Isaiah's own writings that as early as the reign of Uzziah (Isaiah 6:1) the Lord had revealed His majesty to the son of Amoz, and had sent him to bear witness unto Judah. The reigns of Jotham and Ahaz are past, and to the latter king Isaiah had brought the message of deliverance from Pekah and Rezin, which had been fully accomplished, so that Ephraim was now broken and was no more a people (Isaiah 7:8). We may be sure that one so endowed with insight into the divine will had been taken at once into the councils of Hezekiah, and that no one's words had carried more weight. It may well be that Isaiah had advised the struggle for freedom which Hezekiah undertook, and certainly during the fourteen years (2 Kings 18:13) which had elapsed since Hezekiah came to the throne the God-fearing king had done much, may we not say most things, by the advice of the prophet. Hence when the days are darkest, it is to Isaiah he sends as the source of true light.