A young Jedi named Darth Vader, who was a pupil of mine until he turned to evil, helped the Empire hunt down and destroy the Jedi knights.
11 seconds sound clip from the Star Wars: Episode IV - A New Hope (1977) movie soundboard.
You can hear this line at 00:34:14 in the Blu-ray version of the movie.
Quote context
[...]
- Sir, if you'll not be needing me, I'll close down for a while. Sure. Go ahead.
- It's your father's lightsaber.
- He betrayed and murdered your father.
- Now the Jedi are all but extinct.
- Vader was seduced by the dark side of the Force.
(R2-D2 Beep Blip Blip Beep) (2)
[...]