Musannaf Ibn Abi Shayba 37:482

Abu Bakr narrated to us, he said: Waki' narrated to us, from Hisham, from his father, from Abdullah ibn Amr, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, Allah does not take away knowledge by snatching it away from the people. Rather, He takes away knowledge by the death of the scholars, until when no scholar remains, the people will take ignorant leaders. They will be asked, and they will issue fatwas without knowledge, so they will go astray and lead others astray."