​A sincere devotee must, therefore, be prepared to hear the Vedic literature like the Upaniṣads, Vedānta and other literatures left by the previous authorities or Gosvāmīs, for the benefit of his progress. Without hearing such literatures, one cannot make actual progress. And without hearing and following the instructions, the show of devotional service becomes worthless and therefore a sort of disturbance in the path of devotional service. Unless, therefore, devotional service is established on the principles of śruti, smṛti, purāṇa or pañcarātra authorities, the make-show of devotional service should at once be rejected. An unauthorized devotee should never be recognized as a pure devotee.

— Śrīmad-Bhāgavatam 1.2.12 purport