The Advayataraka Upanishad states that the true teacher is a master in the field of knowledge, well-versed in the Vedas, is free from envy, knows yoga, lives a simple life that of a yogi, has realized the knowledge of the Atman (Soul, Self).
Some scriptures and gurus have warned against false teachers, and have recommended that the spiritual seeker test the guru before accepting him. Swami Vivekananda said that there are many incompetent gurus, and that a true guru should understand the spirit of the scriptures, have a pure character and be free from sin, and should be selfless, without desire for money and fame.
According to the Indologist Georg Feuerstein, in some traditions of Hinduism, when one reaches the state of Self-knowledge, one's own soul becomes the guru. In Tantra, states Feuerstein, the guru is the "ferry who leads one across the ocean of existence." A true guru guides and counsels a student's spiritual development because, states Yoga-Bija, endless logic and grammar leads to confusion, and not contentment.
However, various Hindu texts caution prudence and diligence in finding the right guru, and avoiding the wrong ones.
For example, in Kula-Arnava text states the following guidance: