Hazrat Moulana Muhammad Ilyaas (rahmatullahi ‘alaih) once mentioned:
Our deeni elders discourage people who are not bay‘at to pious, learned and experienced mashaayikh from studying the books of the Sufis (as they will not be able to comprehend the knowledge in its correct perspective and this in turn will cause them to fall into confusion and misunderstanding in their deen). As for those who are bay‘at to pious, learned and experienced mashaayikh, they may study the books of the Sufis under the supervision and guidance of their shaikh. In this way, there will be no harm caused to their deen. (Malfoozaat Hazrat Moulana Muhammad Ilyaas (rahmatullahi ‘alaih) pg.57)
Source: Ihyaauddeen.co.za