Next to the king himself, Mordecai was the highest official in the kingdom. He was a popular leader of the Jews, because he helped them in many ways and would even speak to the king for them.
But there won't be any need for the Israelites to cry. Things will be so quiet that not even a dog will be heard barking. Then you Egyptians will know that the LORD is good to the Israelites, even while he punishes you.