video: IskconBangaloreGroup — Lecture by HG Rajeev Lochan Das
Srila Prabhupada, Gorakhpur, February 16, 1971 — [...] Caitanya Mahaprabhu confirms, yei krishna-tattva-vetta sei guru haya [Cc. Madhya 8.128]. Because one who has understood Krishna in truth, he is liberated person.
Therefore he is guru. Guru cannot be a conditioned soul. Guru must be liberated. Because without complete knowledge of Krishna, without being free from the contamination of the three modes of material nature… One cannot understand Krishna on account of his being engrossed with these three material modes of nature.