You know this land is full of people doing wicked things to each other.Heck, even the trailer's too long--more like a short film. ;-) But it did include part of that quote.
I gotta tell you something Wyatt. I told your brothers when they went off to fight, and I suppose the time has come for you. You know I'm a man that believes in the law. After your family, it's about the only thing you've got to believe in. But there are plenty of men who don't care about the law. Men who'll take part in all kinds of viciousness, and don't care who gets hurt. In fact, the more that get hurt the better. When you find yourself in a fight, with such viciousness, hit first if you can, and when you do hit, hit to kill. You'll know. Don't worry. You'll know when it comes to that. The Earps always know.