"Even if one wanders for many millions of years, from the time of creation until the time of annihilation, one cannot get free from the path of material existence unless one receives shelter at the lotus feet of a pure devotee."
(Śrīmad-Bhāgavatam 5.14.41, Purport)
"The human form is an opportunity to take shelter of the bona fide spiritual master and, through him, the Supreme Lord. This Kṛṣṇa consciousness movement has been started to give an opportunity to all the members of human society, who are misled by foolish leaders. No one can get out of this struggle for existence, which is full of miseries, without accepting a pure devotee of the Lord. The material attempt changes from one position to another, and no one actually gains relief from the struggle for existence. The only resort is the lotus feet of a bona fide spiritual master, and, through him, the lotus feet of the Lord."
(Śrīmad-Bhāgavatam 5.14.1, Purport)
"To save oneself, one must take shelter of a pure devotee. Narottama dāsa Ṭhākura therefore says, chāḍiyā vaiṣṇava-sevā nistāra pāyeche kebā. If one wants to save himself from material nature's onslaughts, which arise because of the material body, one must become Kṛṣṇa conscious and try to fully understand Kṛṣṇa. As stated in Bhagavad-gītā (BG 4.9), janma karma ca me divyam evaṁ yo vetti tattvataḥ. One should understand Kṛṣṇa in truth, and this one can do only by serving a pure devotee."
(Śrīmad-Bhāgavatam 7.9.24, Purport)
"To take shelter of the lotus feet of the Lord means to take shelter of the pure devotees. The pure devotees whose only business is serving are honored by the names Prabhupāda and Viṣṇupāda, which indicate such devotees to be representatives of the lotus feet of the Lord. Anyone, therefore, who takes shelter of the lotus feet of a pure devotee by accepting the pure devotee as his spiritual master can be at once purified. Such devotees of the Lord are honored equally with the Lord because they are engaged in the most confidential service of the Lord, for they deliver out of the material world the fallen souls whom the Lord wants to return home, back to Godhead."
(Śrīmad-Bhāgavatam 1.1.15, Purport)
"Everyone is eligible for the supreme destination. In the Śrīmad-Bhāgavatam (SB 2.4.18) it is stated that even the lowest, who are called caṇḍālas (dog-eaters), can be purified by association with a pure devotee. Therefore devotional service and the guidance of a pure devotee are so strong that there is no discrimination between the lower and higher classes of men; anyone can take to it. The most simple man taking shelter of the pure devotee can be purified by proper guidance."
(Bhagavad-gīta As It Is 9.32, Purport)
"It is stated here that this confidential knowledge is extremely difficult to understand, yet it is very easy to understand if one takes shelter of a pure devotee. This confidential knowledge is also mentioned at the end of Bhagavad-gītā, where the Lord says, sarva-dharmān parityajya mām ekaṁ śaraṇaṁ vraja: (BG 18.66) 'Abandon all varieties of religion and just surrender unto Me.' This knowledge is an extremely confidential secret, but it can be understood if one approaches the Supreme Personality of Godhead through the bona fide agent, the spiritual master in the disciplic succession from Nārada."
(Śrīmad-Bhāgavatam 7.6.27, Purport)
"Because the common man is unable to control the senses and the mind, it is his duty to seek the shelter of a great soul or a great devotee of the Lord and just try to please him. That will make his life perfect. A common man cannot rise to the topmost stage of spiritual perfection simply by following the rituals and religious principles. He has to take shelter of a bona fide spiritual master and work under his direction faithfully and sincerely; then he becomes perfect, without a doubt."
(Śrīmad-Bhāgavatam 3.22.6, Purport)
"The summary is that one has to, first of all, seek the association of pure devotees who not only are learned in the Vedanta but are self-realized souls and unalloyed devotees of Lord Śrī Kṛṣṇa, the Personality of Godhead. In that association, the neophyte devotees must render loving service physically and mentally without reservation. This service attitude will induce the great souls to be more favorable in bestowing their mercy, which injects the neophyte with all the transcendental qualities of the pure devotees."
(Śrīmad-Bhāgavatam 1.5.34, Purport)
"The parampara system of disciplic succession is very important as a means of spiritual success. One becomes a mahat by the grace of his mahat spiritual master. If one takes shelter of the lotus feet of a great soul, there is every possibility of one's also becoming a great soul."
(Śrīmad-Bhāgavatam 3.22.6, Purport)