Isaiah 37:6

And Isaiah said unto them, when they had presented their message, Thus shall ye say unto your master, Thus saith the Lord, Be not afraid of the words that thou hast heard, wherewith the servants, literally, "the youths," a disparaging designation characterizing their empty boasting, of the king of Assyria have blasphemed Me, that being the real and grievous offense committed by Rabshakeh's embassy.