And you mustn't worry. I want you to be good in this picture.

5 seconds sound clip from the A Star is Born classic radio play.

You can hear this line at 00:39:17 in the radio play.

Quote context

[...]

- How's Norman?

- He's... Well, he's trying awfully hard.

- Has he been...? Is he all right?

- He's gone to a sanatorium.

- You see, he really wants to stop drinking. And I think he could, only...

- Well, perhaps if he were going to work again, it'd be some encouragement.

- Oliver, could you...? Could you do that?

- Hm! I might be able to manage it.

- Oh, thank you. But he mustn't ever know I told you.

- He won't know.

- And you mustn't worry. I want you to be good in this picture.

- I'll try, Oliver. That's the least I can do for you.

- And one more for the book, folks! What star recently released from a sanatorium where he underwent a 'rest cure' is now hanging around the Santa Anita racetrack while he gets into shape for a comeback?

- Your guess is as good as mine... and mine's no guess.

- Hello, Charlie.

[...]