mahot-krpa bina kono karme 'bhokti 'noy krsna-bhokti dure rohu samsar nahe kkhoy (C.C. Madhya 22/51.)
Unless one is favoured by a pure devotee, he cannot attain the platform of devotional service. To say nothing of Krsna-bhakti, or loving devotional service to Krsna, one cannot even be free from the entanglement of material existence
My most worshipful spiritual master, His Divine Grace Srila Bhaktisiddhanta Sarasvati Prabhupada comments on this verse in his 'Anubhasya' : "It is impossible to cultivate devotional service to Sri Krsna, which is absolutely transcendental, by executing fruitive pious activities which are mundane performances although they are recommended in the karmakanda section of the Vedas. Only by receiving the mercy of a devotee of Lord Krsna is it possible to develop the eligibility to engage in devotional service . Devotion to Sri Krsna is almost a dream, because even the shackles of material existence cannot be cut by any other means. Compassion is not to be found in any other living being other than in a vaisnava, pure devotee of Krsna. He alone is the transcendental being amongst all others. By mundane consideration some materialists think that a vaisnava is a mundane personality like them, but in truth the devotee of Krsna, who has renounced the material world is an incomparable superexcellent being. Knowing him to be a true wellwisher of all living entities if one prays to him for mercy then one becomes free from all material desires and attractions for sense gratification and one becomes then a fit candidate for engaging in the transcendental loving service of the Supreme Lord Krsna."
Excerpted from the "Sadhu-Sanga", Chapter One.