I'm afraid you might hurt yourself, Regan.
4 seconds sound clip from the The Exorcist movie soundboard.
You can hear this line at 01:24:33 in the Blu-ray version of the movie.
Quote context
[...]
- Oh, God, can't you help her? Just help her!
- I'm a friend of your mother's. I'd like to help you.
- You might loosen these straps, then.
- I'm afraid you might hurt yourself, Regan.
- Well, then, let's introduce ourselves. I'm Damien Karras.
- And I'm the devil. Now, kindly undo these straps.
[...]