This quote did not appear in any film.
It is believed that Rick played by Humphrey Bogart, says this phrase to the pianist of his cafe in the film Casablanca (1946), but in any moment he mentions it and it is a misquotation.
In the script this is what it is really said according to an excerpt of the dialogue between Ilsa, played by Ingrid Bergman and Sam, Dooley Wilson:
'Ilsa: Play it once, Sam. For old times' sake.
Sam: I don't know what you mean, Miss Ilsa.
Ilsa: Play it, Sam. Play "As Time Goes By."
Sam: Oh, I can't remember it, Miss Ilsa. I'm a little rusty on it.
Ilsa: I'll hum it for you... do dah, dah, dah, daaah...
Ilsa: Sing it, Sam.'

There is a film directed by Woody Allen in 1972 named after this famous misquotation.