That's the old Quaker spirit, Mother Lord. Now, keep swinging.

5 seconds sound clip from the The Philadelphia Story movie soundboard.

You can hear this line at 00:23:38 in the Blu-ray version of the movie.

Quote context

[...]

- Oh, dear, you both better dress. And please, both of you, promise to behave like ladies in front of these creatures.

- We'll do our best, Mrs. Lord. I don't know how good that is.

- Dexter, how perfectly dreadful.

- And what'll they say about Seth not being here for his own daughter's wedding?

- I know, darling.

- You better go and tell them how terribly, terribly happy we are to have them.

- That's the old Quaker spirit, Mother Lord. Now, keep swinging.

- Oh. I thought it was that butler.

- The family will be down to welcome you in a moment.

- What with?

- With open arms.

- They're terribly, terribly happy to have any friends of Junius's here.

- They don't know about us, do they?

- No. Why should they?

[...]