مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3672
Musnad of Abdullah bin Mas'ood
It was narrated that Abu wa'il said: I was sitting with "Abdullah and Abu Moosa, and they said: The Messenger of Allah (ﷺ) said: “Ahead of the Hour will be days during which ignorance will appear and knowledge will be taken away, and there will be a lot of harj." We said: What is harj? He said: "Killing."
Musnad Ahmad 3695Its isnad is saheeh, al-Bukhari (7062) and Muslim (2672)]