1. “Gurus” who speak without reference to sastra

    This is guru. Guru means he'll always enlighten the disciples with the light of sastra. Not that he will say, "There is no need of sastra. I am incarnation. I, whatever I speak, you take it." No. This is rascal. You should immediately, who has no reference to the sastra, immediately take him as a rascal number one. This is the conclusion.

    From Srila Prabhupada's lecture on Bhagavad-gita 1.24–25 — July 20, 1973