Source: http://www.prabhupadaconnect.com/Srila-Prabhupadas-Divine-Lotus-Feet.html
“The lotus feet of our spiritual master are the only way by which we can attain pure devotional service. I bow to his lotus feet with great awe and reverence. By his grace one can cross the ocean of material suffering and obtain the mercy of Krishna.”
(Sri Guru-vandana Verse 1, Srila Narottama dasa Thakura)
“The dust of the feet of a devotee, the water that has washed the feet of a devotee, and the remnants of food left by a devotee are three very powerful substances. By rendering service to these three, one attains the supreme goal of ecstatic love for Krishna. In all the revealed scriptures this is loudly declared again and again. Therefore, my dear devotees, please hear from me, for I insist again and again: please keep faith in these three and render service to them without hesitation. From these three one achieves the highest goal of life—ecstatic love of Krishna. This is the greatest mercy of Lord Krishna.”
(Caitanya-caritamrita Antya 16.60-63)
“In the neophyte stage, in the intermediate stage, or in the fully advanced perfected stage, one can make the function of the head perfect by bowing down before the Lord or His representative. Similarly, he can perfect the function of the eyes by seeing the Lord and His representative. In this way, everyone can elevate the functions of the different parts of his body to the highest perfectional stage simply by engaging them in the service of the Lord or His representative. If one is able to do nothing more, he can simply bow down before the Lord and His representative and drink the caranamrta, the water which has washed the lotus feet of the Lord or His devotee.”
(Krishna Book, Chapter 80)
“The stage of pure devotion is attained by sincerely serving a pure devotee of the Lord. The first condition of devotional service to the Lord is therefore to be a servant of a pure devotee, and this condition is fulfilled by the statement ‘reception of the dust of the lotus feet of a pure devotee who has also served another pure devotee.’ That is the way of pure disciplic succession, or devotional parampara.”
(Srimad-Bhagavatam 2.3.23, Purport)
“In Srimad-Bhagavatam it is also confirmed by Prahlad Maharaj that merely by personal efforts or by the instructions of higher authorities one cannot attain to the stage of devotional service. One must become blessed by the dust of the lotus feet of a pure devotee who is completely freed from the contamination of material desires.”
(Srila Prabhupada Lecture, Los Angeles, June 20, 1972)
“One cannot come to the precincts of Krishna consciousness unless he touches the dust of the lotus feet of a person who has become a mahatma, a great devotee. This is the beginning of the surrendering process. Lord Krishna wants everyone to surrender unto Him, and this surrendering process begins when one touches the lotus feet of a bona fide spiritual master. By sincerely rendering service to a bona fide spiritual master, one begins his spiritual life in Krishna consciousness. Touching the lotus feet of a spiritual master means giving up one’s false prestige and unnecessarily puffed-up position in the material world.”
(Srimad-Bhagavatam 4.26.20, Purport)
“Unless human society accepts the dust of the lotus feet of great mahatmas— devotees who have nothing to do with material possessions—mankind cannot turn its attention to the lotus feet of Krishna. Those lotus feet vanquish all the unwanted, miserable conditions of material life.”
(Caitanya-caritamrta Madhya 22.53)
“God is called Bhagavan. Bhagavat, the original word is bhagavat, and one who has got intimate relation with Bhagavan, he is called bhagavat. So here it is recommended, bhagavatanghri-renum na jatu martyah. Martya means one who will die. Every one of us will die. But abhilabheta yas tu. But we can achieve a great success. Although this body is mortal, we can get, we can achieve a great success. And what is that? To take the dust of the lotus feet of a bhagavata. Simple thing.”
(Srila Prabhupada Lecture, Los Angeles, June 20, 1972)
“One cannot become happy by accepting a false guru. A guru should be accepted as advised in Srimad-Bhagavatam. Tasmad gurum prapadyeta jijnasuh sreya uttamam: One should approach a bona fide guru to inquire about the highest benefit of life. Such a guru is described as follows: sabde pare ca nisnatam. Such a guru does not manufacture gold or juggle words. He is well versed in the conclusions of Vedic knowledge. He is freed from all material contamination and is fully engaged in Krishna’s service. If one is able to obtain the dust of the lotus feet of such a guru, his life becomes successful. Otherwise he is baffled both in this life and in the next.”
(Srimad-Bhagavatam 5.14.13, Purport)
“The pure devotees whose only business is serving are honored by the names Prabhupada and Visnupada, 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. Such pure devotees are better known as vicelords according to revealed scriptures. The sincere disciples of a pure devotee consider him equal with the Lord, but the pure devotee always considers himself to be a humble servant of the servant of the Lord. This is the pure devotional path.”
(Srimad-Bhagavatam 1.1.15, Purport)