(5) باب رَفْعِ الْعِلْمِ وَقَبْضِهِ وَظُهُورِ الْجَهْلِ وَالْفِتَنِ فِي آخِرِ الزَّمَانِ
Abu Huraira reported Allah's Messenger (ﷺ) having said:
The time would draw close to the Last Hour and knowledge would decrease. The rest of the hadith is the same.
Reference: Sahih Muslim 157 f
In-book reference: Book 47, Hadith 20
USC-MSA web (English) reference(deprecated numbering scheme): Book 34, Hadith 6460