I was just thinking what a bonehead play that old jackass made when he put all his goods in our keeping.

5 seconds sound clip from the The Treasure of the Sierra Madre movie soundboard.

You can hear this line at 01:31:40.901 in the Blu-ray version of the movie.

Quote context

[...]

- I figure we can reach the high pass in 2 days more. After that, it'll be 3 or 4 days to the railroad. That's figuring no hard luck on the trail, of course.

(Dobbsy laughing)

- What's the joke, Dobbsy?

- Aren't you going to let me in on it?

- In on it? Sure, I will. Sure.

- Well, go ahead and spill it. What's so funny?

- I was just thinking what a bonehead play that old jackass made when he put all his goods in our keeping.

- How do you mean? (2)

- Figured let us do his sweating for him, did he?

- Well, we'll show him.

- What are you getting at?

[...]