The whole thing was a plot!
4 seconds sound clip from the Cinderella (1950) movie soundboard.
You can hear this line at 00:59:04 in the Blu-ray version of the movie.
Quote context
[...]
- You were in league with the Prince all along.
- I tried to stop her, but she vanished into thin air.
- All we could find was this glass slipper.
- But, Sire, he loves her. He won't rest till he finds her. He's determined to marry her.
- The Prince, Sire, swears he'll marry none but the girl who fits this slipper.
- He said that, did he? We've got him!
- But, Sire, this slipper may fit one of any number of girls.
[...]