مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3794
Musnad of Abdullah bin Mas'ood
It was narrated that ‘Abdullah and Abu Moosa al-Ash'ari (رضي الله عنه) said: The Messenger of Allah (ﷺ) said: “Ahead of the Hour there will be some days in which knowledge will be taken away and ignorance will prevail, and there will be a lot of harj." He said: And harj means killing.
Musnad Ahmad 3817Its isnad is saheeh, al-Bukhari (7062) and Muslim (2676)]