Withdraw your guard, and I shall tell you where your doom will be decided! I will not be held prisoner here!
Source: The Lord of the Rings: The Return of the King (2003 New Line film, extended edition)
Notes: Spoken to Gandalf, who is interrogating him about where Sauron will attack after the Ents take him prisoner in his tower. After he says this, Grima Wormtongue repeatedly stabs him in the back, causing him to fall off the top of Orthanc onto a spiked wheel. This scene only takes place in the Extended edition; in the original film, Gandalf decides to leave Saruman at Isengard, and his fate is left unresolved.