It's not a bank. It's a fortress there.
3 seconds sound clip from the For a Few Dollars More movie soundboard.
You can hear this line at 00:31:04.681 in the Blu-ray version of the movie.
Quote context
[...]
- I don't doubt that, but I have a large sum to deposit.
- A very dangerous bandit with a gang of killers.
- What would be the most impossible bank for me to rob?
- It's not a bank. It's a fortress there.
- What time's the next train for El Paso?
- 11:30.
- I'll telegraph to my colleague in the Bank of El Paso that you're going to arrive.
- Thanks.
- Hey, mister. Captain. General. Welcome. Do you need a stable or a room? Do you want to take a bath?
- My name is Fernando. The stable is right here. And that is your hotel.
[...]