You do that. It's your duty.
4 seconds sound clip from the The Quiet Man (1952) movie soundboard.
You can hear this line at 02:01:24 in the Blu-ray version of the movie.
Quote context
[...]
- It's a big fight in the town!
- There's a big fight in this fish right here.
- I'd put a stop to it, but see...
- You do that. It's your duty.
- But you see, it was Danaher and Sean Thornton!
- Who?
- Why the devil didn't you tell me?
- Father, shouldn't we put a stop to it now?
- We should, lad, yes, we should. It's our duty, yes, it's our duty.
[...]