system
A chat on subreddit /r/NoStupidQuestions
human
Many that live deserve death. And some that die deserve life. Can you give it to them? Then do not be too eager to deal out death in judgement. For even the very wise cannot see all ends.
gpt
I realize that many Redditors already know this, but for those who don't, that's a quote from Gandalf in Lord of the Rings, in response to Frodo lamenting that Bilbo hadn't killed Gollum

It was also the first quote that came to my mind when I read the question. It had a big influence on me as a teenager as I started forming concrete views on the death penalty.