Quote from : Star Wars: Episode VI - Return of the Jedi Movie

Moff Jerjerrod: The Emperor's coming here?
Darth Vader: That is correct, Commander. And, he is most displeased with your apparent lack of progress.
Moff Jerjerrod: We shall double our efforts.
Darth Vader: I hope so, Commander, for your sake. The Emperor is not as forgiving as I am.