It is reported that Imām ‘Abd Al-Raḥmān b. Mahdī – Allāh have mercy on him – said, following a mention of the Ṣȗfīah (Sufis):

Do not sit with them, nor with the followers of Kalām.(1) Be with the carriers of books,(2) for they are like mines, like those who descend: one brings up a gem and another a nugget of gold.

Ibn Battah, Al-Ibānah Al-Kubrā article 483.

(1) Speculative theology, drawn from foreign philosophy and logic, as practiced by sects such as the Jahmia and Mutazila.

(2) Arabic al-qamātir: covers or folders used to keep written material. ‘Carriers of books’ refers to the scholars and students who occupied themselves with Islamic knowledge and hadīth.