The title pretty much says it all. I know there are a couple of stories like this but the one in particular I'm looking for has Nathan and Ezra arguing about a poker game in the saloon. After they argue some old friends of Nathan find him in the saloon. These 'friends' then try to lynch Ezra. I remember that at one point after Nathan saves Ezra he says something like "no friends of mine try to kill my other friends". It was a really good friendship story featuring Nathan and Ezra.
Found this while randomly reading stories on blackraptor...It's part of Yolande's Weight to Bear series:
http://www.blackraptor.net/yolande/bear/Bear_Nathan.htm