- But why won't you tell me where she is?
- Because there's an unwritten law in our family against snitching.

8 seconds sound clip from the You Can't Take It with You (1939) classic radio play.

You can hear this line at 00:48:25 in the radio play.

Quote context

[...]

- Alice is right. She can't come back here. She'd be miserable.

- Mr. Blakely, please. We'll find a place where she is and...

- Hello, Mr. Blakely? This is Mr. Vanderhof.

- Still want to buy the house? All right. Draw up the papers. That's all right.

- Quite a crook, that fellow.

- But why won't you tell me where she is?

- Because there's an unwritten law in our family against snitching.

- And Alice doesn't want to see you, Tony.

- Grandpa, is the moving man down there?

- He just took out the xylophone.

- Pretty busy today here, son. Moving and all.

- Now, if you see Alice, will you tell her that I've quit the banking business and I'm gonna work on that grass thing?

- Grass, sure.

[...]