You can mention the specifics regarding why you’re declining the position, like salary, the company’s attitude, you took a different position, etc., but you don’t have to if you don’t want to. If you do choose to give your reasoning, though, Adrian Granzella Larson at The Muse recommends you keep it brief. A quick sentence will do. There’s no need to mention any of the things you didn’t like about the people you met, the workplace, or the company itself. You can also offer referrals if you have any, but it’s not necessary unless they ask. Remember, short and sweet.
Some games, like ancient stories retold by orators through the years, were merely passed down from generation to generation. Nobody knew where most of the games originated, but everybody had them. Every week it seemed like there was a new game to acquire, and kids with the hottest collections of TI games—like me—had people lining up in the hallway. Like a shady back alley deal, kids would approach me at lunch and ask if I had anything new. “Yeah, I got the hookup,” I’d say, “But what you got for me?” I’d like to think that somewhere in the country a kid is playing a game I once passed down from my very own TI-83 Plus.