Your interest is very gratifying, sir.
4 seconds sound clip from the Dark Command (1940) movie soundboard.
You can hear this line at 00:06:07 in the Blu-ray version of the movie.
Quote context
[...]
- That's all very interesting, but are you going to move this wagon, or shall I have it moved for you?
- Your interest is very gratifying, sir.
- First time our singing lessons have ever held up traffic.
- If you'd care to, we'd be delighted to have you join us.
- Thank you, mister. In that case, I reckon we'll move on.
[...]