Advice for the seekers of knowledge–beware of [التنَطُّع]; [التعمُّق] and [ بدع ]
Abdullaah Ibn Mas’ood (radiyallaahu-anhu) said:
Acquire knowledge before it is taken away and it being taken away is the departure of its people (i.e. the death of the scholars). Indeed, beware of [التنَطُّع (i.e. going beyond what Allaah has legislated with regards to one’s practice of the religion); التعمُّق (i.e. looking too deeply into affairs in a manner that leads a person to overstep the boundaries of the legislation) and بدع (innovation in religion). And upon you is (to hold onto the) ancient affair (i.e. the way of the Salaf).
Bayhaqiy (rahimahullaah) in Al-Madkhal Ilaa As-Sunan Al-Kubraa Number: 387
Ad-Daarimiy (rahimahullaah) in As-Sunan 1/54
Ibn Abdul Barr (rahimahullaah) in Jaami Bayaan al-Ilm 1/152
Al-Khateeb (rahimahullaah) in Al-Faqeeh Wal-Mutafaqqih 1/43