Musnad Ahmad 1647

It was narrated that Sa"eed bin Zaid said: The Messenger of Allah (ﷺ) mentioned (i.e., warned against) turmoils (fitnahs) like pieces of dark night. I think he said: "People may rush to become involved in them very quickly.” It was said: Are all of them (those who get involved in them) doomed or some of them? He said: "The killing will be enough (reason) for them (all to be doomed).”