Looking for a film - this is the scene I am trying to find, possibly from spaghetti western.. Clint?

this is how I remember the scene.

Two sweaty cowboys sitting in a saloon.

One old (possibly retired) gunslinger is being coaxed out of retirement.

The gunslinger grabs some flies that on the table and slowly opens hand to reveal 3 or 4 dead flies.

The persuader says something like "Hey, you are still fast"

Gunslinger says "Yeah but when I was younger I would have got all 7 of them"

What was the film please?