- But what could he do without you?
- There's no limit to what he could do. He could destroy the earth.

Klaatu (Michael Rennie)

8 seconds sound clip from the The Day the Earth Stood Still (1954) classic radio play.

You can hear this line at 00:45:31 in the radio play.

Quote context

[...]

- Where can you go?

- I'm sure Barnhardt can arrange to hide me until the meeting tonight.

- Where is it going to be?

- At the ship.

- Now, look there... army cars.

- Full troops in full gear.

- The alarm is out all right.

- It's only a few more blocks to Professor Barnhardt's.

- I'm worried about Gort. I'm afraid of what he might do if anything should happen to me.

- Gort? But he's a robot.

- He's a product of centuries of refinement.

- But what could he do without you?

- There's no limit to what he could do. He could destroy the earth.

- And the city is swarming with patrol cars... hunting you.

- How can we tell them?

- They won't listen. You must listen!

- If anything happens to me, you must go to Gort. You must give him this message: 'Klaatu barada nikto. Gort, Klaatu barada nikto.' Say it!

- Gort, Klaatu barada...

- Nikto!

- Gort, Klaatu barada nikto.

[...]