Bhagavatapurana 3.7.38

3.7.38

puruṣasya ca saṃsthānaṃ svarūpaṃ vā parasya ca /
jñānaṃ ca naigamaṃ yat tad guru-śiṣya-prayojanam //

38. The true nature of the Jiva and the essential state of Paramatman, the knowledge to be derived from the Upanishads and what constitutes the purpose of the master and the pupil;