John Gill Commentary 2 Kings 22:18

"But unto the king of Judah, who sent you to inquire of Jehovah, thus shall ye say to him, Thus saith Jehovah, the God of Israel: As touching the words which thou hast heard," — 2 Kings 22:18 (ASV)

But to the king of Judah, which sent you to inquire of the
Lord
That is, with respect to him, or what may concern him:

thus shall you say to him ;
carry back this message to him as from the Lord he desired to inquire of:

thus saith the Lord God of Israel, as touching the words which you
have heard :
read out of the law, concerning the destruction of the land, and its inhabitants threatened therein.