Isaiah 36:12

‘But the Rabshakeh said, “Has my master sent me to your master and to you to speak these words? Has he not sent me to the men who sit on the wall, those who will shortly eat their own excrement and drink their own urine with you?” '

The Rabshakeh's reply is that it was in fact to these people that his master wanted to send his message. It was not intended to be an official secret, it was intended to be received by all. Then he points out to the people the straits to which the siege will soon bring them. They will have nothing to eat and drink but their own excrement and urine (‘waters of the feet'). ‘With you.' It will eventually be true of the leaders too.

There may in all this be an intended contrast, stressing the polite diplomacy of Judah, and the arrogant and crude diplomacy of Assyria. Judah are clearly gentlemen, whereas Assyria are merely bullies.