Sahih Muslim Book 34, Hadith Number 6465.

Chapter : Knowledge would be taken away and ignorance would prevail upon people and the turmoil at the end of the world.

‘Urwa b. Zubair reported that ‘Aisha said to him: This news has reached me that ‘Abdullah b. ‘Amr al-‘As would pass by us during the Hajj season, so you meet him and ask him (about religious matters) as he has acquired great knowledge from Allah’s Messenger (may peace be upon him). I thus met him and asked him about things which he narrated from Allah’s Messenger (may peace be upon him). And amongst these the one he mentioned was that Allah’s Apostle (may peace be upon him) said: Verily, Allah does not take away knowledge from people directly but he takes away the scholars and consequently takes away (knowledge) along with them and leaves amongst persons the ignorant as their leaders who deliver religious verdicts without (adequate) knowledge and themselves go astray and lead others astray. ‘Urwa said: When I narrated this to ‘Aisha, she deemed it too much (to believe) and thus showed reluctance to accept that (as perfectly true) and said to ‘Urwa: Did he (‘Abdullah b. ‘Amr) say to you that he had heard Allah’s Apostle (may peace be upon him) as saying: (‘Urwa had forgotten to ask this from ‘Abdullah b. ‘Amr). So when it was the next year, she (‘Aisha) said to him (‘Urwa): Ibn Amr has come (for Hajj), so meet him; talk to him and ask him about this hadith that he narrated to You (last year on the occasion of the Hajj) pertaining to knowledge. He (‘Urwa), said: So I met him, and asked about it and he narrated to me exactly like one that he had narrated (to me) for the first time. So when I informed her (‘Aisha) about that, she said: I do not think but this that he has certainly told the truth and I find that he has neither made any addition to it, nor missed anything from it.