''The direct approach to Krishna is not safe or easy; it can sometimes be terribly risky, if there is anything in the sadhak that interferes with the clarity and singleness of his attitude. In that case any wrong desire, vanity, pride, sexual impurity, ambition, or any other pronounced weakness may open the way to serious distortion of the sadhana, turning into wrong ways, breakdown or collapse, even to spiritual perdition. 

Krishna's own influence cannot be a wrong influence, if it is really his, but it is easy to mistake and accept some other influence as his. Especially, he is the Lord of Love and Beauty and Delight, and nothing is easier for men who are always going in the wrong way in search of these things, to bring their wrong ways into their search for him also. 

That experience must be one of the reasons why the seers insist on the approach through the guru and say that Krishna cannot be attained otherwise. It is the reason why they insist on vairagya, detachment from the ordinary aims and ends of human nature as so necessary. 

That is also why Krishna does not like to show himself until the field is clear for him! The intervention of some power or influence that represents itself as he, even puts on an imitation of his form or voice would be fatal if accepted; but even his real manifestation might bring about an upset in someone not really ready for it. One must be on guard against these dangers and it is the guru who can interpose himself as a shield against them. ''

Sri Aurobindo [extract - Bhakti Yoga and Vaishnavism -Letters on Yoga -2]

Bhagavata Purana Kangra series circa 1820-30 : Lord Krishna lures Kayavana to the cave of Muchukunda, where he is burnt to ashes by the awakened sage.