‘Lord Krishna recommends the same procedure in the “Bhagavad-Gita”, tad viddhi pranipatena pariprasnena sevaya [Bg. 4.34]. “One must offer obeisances to the guru, inquire from him, and serve him.” If you simply go and ask the spiritual master questions in a challenging spirit but do not accept his instructions and do not render service, then you’re wasting your time. The word used here is pranipatena, “offering obeisances with no reservation.” So reception of transcendental knowledge is based on this pranipata. That is why Krishna says later, sarva-dharman parityajya mam ekam saranam vraja. [Bg. 18.66] “Give up everything else and just surrender unto Me.” Just as we have to surrender to Krishna, we have to surrender to Krishna’s representative, the spiritual master.
<…> One should approach a guru to learn about tattva, the Absolute Truth, not to acquire some material benefit. One should not search out a guru to cure some material disease. For that there is a medical practitioner. Why should you search out a guru for that purpose? A guru is one who knows the Vedic sastras, or scriptures, and who can teach us to understand Krishna.
Srila Prabhupada’s lecture on November 1974, Mumbai,