"I don't know! It was just some random berries Foster found. I made it into a smoothie to see what it would do but I didn't think it would kill him!!"

If he wasn't a demon he might worry about going to hell over something like this. Though, even as a demon he still really wanted to avoid going to hell ever again. That place was a total shit hole!

"I don't need anything, we just. We need to get him to the clinic."

And it's obvious when he says the clinic which one he means. Zecora is the only doctor they know who would be able to help them in anyway.