Isaiah 36:21,22

‘But they held their peace and did not answer him a word, for the king's command was, “Do not answer him”.' Then Eliakim, the son of Hilkiah, who was over the household, and Shebna the scribe, and Joah, the son of Asaph, the recorder, came to Hezekiah with their clothes torn, and told him the words of the Rabshakeh.'

His words were heard in disdainful silence. They returned no answer because Hezekiah had commanded that no reply be given. The matter was not to be decided in front of the people, and time for thought was required. The disdainful silence was also a reply to the insults of the Rabshakeh.

So the three went to Hezekiah bearing the message that they had been given, symbolically tearing their clothes to indicate their mourning over the content of the message. It would also alert the king to the fact that the message they brought was negative. And they told him what had been said.