A confidential source has passed on the rumor that he's been summoned to Washington for a super-secret assignment. It's only a rumor, remember.

6 seconds sound clip from Superman (1948) - The Reducer Ray (Chapter 3).

You can hear this line at 00:05:04.937 in the Blu-ray version of the episode.

Quote context

[...]

- Nice bit of reporting you did. Little underhanded, of course, but still nice.

- Well, I'm sorry, but my getting a job depended on it.

- Oh, by the way, what about that job?

- You've been on the payroll for hours.

- Now, perhaps we could have some teamwork around here.

- We will.

- Fix him up with a desk.

- And here's the latest about the most glamorous figure that's ever flashed across the news horizon. Yes, you guessed it, Superman.

- A confidential source has passed on the rumor that he's been summoned to Washington for a super-secret assignment. It's only a rumor, remember.

- Now for other important news of the day...

- The Spider Lady.

- Did you hear that broadcast?

- Yes.

- The government's calling in Superman, there can be only one reason. They've perfected the ray machine and want him to guard it.

- It'll make tougher for us to get ahold of it.

[...]