Question

Hello, honored Rabbi,
I’m currently watching the series “The Holy One, Blessed be He, and the World,” and I’m learning a lot and enjoying it מאוד, thank you.
I know many people don’t like being asked for sources, so I’d appreciate it if you’d forgive me. In lesson 5, the Rabbi mentions the words of Rabbeinu Chananel on Chagigah 5, that a person who kills his fellow is not acting under a decree of Heaven, and about this it says, “and there are those who perish without justice.” I looked at the source but didn’t find what I was looking for.
I know the Rabbi’s view is that mentioning the opinion among the medieval authorities is not the main thing, and one does not rely on that alone, but only notes that they too held this way. Even so, I’d be happy to know whether there is a source for this idea in Rabbeinu Chananel, to strengthen it for me and for others. I am still captive to an old prejudice—what can I do—especially in light of what is mentioned by the medieval authorities, that the words of Rabbi Chananel are received tradition, meaning they were transmitted through tradition, and therefore their importance is great.
Thank you very much, may there be good tidings, and again, sorry for the bother.