(21) باب رَفْعِ الْعِلْمِ وَظُهُورِ الْجَهْلِ
Narrated Anas:
Allah's Messenger (ﷺ) said, "From among the portents of the Hour are (the following): -1. Religious knowledge will be taken away (by the death of Religious learned men). -2. (Religious) ignorance will prevail. -3. Drinking of Alcoholic drinks (will be very common). -4. There will be prevalence of open illegal sexual intercourse.
Reference: Sahih al-Bukhari 80
In-book reference: Book 3, Hadith 22
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 3, Hadith 80