It is reported that Ḥabīb b. ʿUbayd - Allāh have mercy on him - said:

Learn knowledge, understand it and benefit from it (live by it); and do not study it in order to decorate yourself with it, for if you live long you will likely see a time when knowledge will be used for beautification like a man beautifies himself with his garments.

Ibn Al-Mubārak, Al-Zuhd wa Al-Raqāʾiq no. 1056