You bargain and trifle with your own nature. That's your error.
5 seconds sound clip from the The Big Knife (1955) movie soundboard.
You can hear this line at 01:14:37 in the Blu-ray version of the movie.
Quote context
[...]
- You swat the fly on my nose with a hammer! Throw it away.
- Do you know where your fatal error lies? You ought to know, so I'm going to tell you.
- You're afflicted with a fine, fat case of merchant psychology.
- You bargain and trifle with your own nature. That's your error.
- Tonight, you're about to possibly destroy your life and certainly mine.
- Didn't we pick each other out of millions?
- Where's the rich, full-hearted woman I know you to be?
[...]