A gentleman doesn't smoke in the presence of a lady.
4 seconds sound clip from the Stagecoach (1939) movie soundboard.
You can hear this line at 00:22:29 in the Blu-ray version of the movie.
Quote context
[...]
- Thank you, son. Professional compliments are always pleasing.
- What happened to that boy, whose arm I fixed?
- Put out that cigar! You're annoying this lady.
- A gentleman doesn't smoke in the presence of a lady.
- Be careful of old Bessie up there, now.
[...]