Madam! I am not in the habit of substituting for spurious Santa Clauses. No!
6 seconds sound clip from the Miracle on 34th Street (1947) movie soundboard.
You can hear this line at 00:06:02 in the Blu-ray version of the movie.
Quote context
[...]
- Wake me up when the parade starts.
- Jingle bells, jingle bells, jingle all the way...
- Shameful. Absolutely shameful.
- Could you be Santa Claus? Have you had any experience?
- Oh, please. You've got to help me out.
- Madam! I am not in the habit of substituting for spurious Santa Clauses. No!
- Well, the-the children mustn't be disappointed. All right. I'll do it.
- Oh, good. Thank you. Come along. Right this way.
[...]