The Messenger of Allah ﷺ said, "Tribulations will appear, killing will increase, and knowledge will be taken away."When Umar heard Abu Hurayrah say, "Knowledge will be taken away," Umar remarked, "It will not be torn out from the hearts of the scholars, rather the scholars themselves will pass away."
أن رسول الله ﷺ قال: تظهر الفتن، ويكثر الهرج، ويرفع العلم. فلما عمر سمع أبا هريرة يقول: يرفع العلم. قال عمر: أما إنه ليس ينزع من صدور العلماء، ولكن يذهب العلماء.
Imam Ahmad (10231) narrated it from Waki, from Jafar bin Barqan, from Yazid bin Asam, from Abu Hurairah, who mentioned it. Its isnad is sahih. Haythami said in Majma al-Zawaid (1/202), after attributing it to Bazzar as well, "Its narrators are the narrators of the Sahih."