No speeding. You don't want any cops stopping you with him in the back.

6 seconds sound clip from the Double Indemnity movie soundboard.

You can hear this line at 00:52:39 in the DVD version of the movie.

Quote context

[...]

- I said, don't worry, Walter.

- You start as soon as the train leaves.

- When you get to the refinery, turn off the highway onto the dirt road.

- From there it's exactly eight-tenths of a mile to the dump beside the tracks. Remember.

- I remember everything.

- No speeding. You don't want any cops stopping you with him in the back.

- Walter, we've been through all that so many times.

- When you leave the highway, turn off all your lights.

- I'll be back on the observation platform. I'll drop off as close to the spot as I can.

- Let the train pass, then dim your lights twice.

[...]