Sri Chaitanya Mahaprabhu begins his teaching to Sanatana Goswami by explaining that the soul wanders the universe, life after life, and then in one special life, by the grace of Krishna and the guru, he begins the journey of bhakti.
When Srila Rupa Goswami wrote about the sixty-four elements of bhakti, the first five on the list are related to the guru and disciple; and when Sanatana Goswami wrote his Hari Bhakti Vilasa along with his friend Gopala Bhatta Goswami, the first two of twenty chapters in the manual explain the guru and disciple relationship. This is a brief extract of his quotations from several scriptures.
“The human body is a ship, the guru is the captain, the instructions of God are the favourable winds.” – Srimad Bhagavatam 11.20.17
“Any person who desires happiness must seek a guru and take shelter of him. The qualification of the guru is that he has realised the conclusions of scripture and is able to convince others.” – Srimad Bhagavatam 11.3.21
“One should approach a guru who is in full knowledge of me as I am, who is peaceful, and who by spiritual elevation is non-different from me.” – Srimad Bhagavatam 11.10.5
“To learn about transcendence one must approach the guru with wood in his hands for the fire sacrifice. The symptom of such a guru is that he is expert in the Vedas and therefore he constantly engages in the service of God.” – Mundaka Upanishad 1.2.12
“The disciple should be free from false prestige, active, never lazy, and should give up all proprietorship. He should have feelings of friendship towards the guru, and should not become bewildered or deviated. The disciple should always desire advancement in spiritual understanding, should not not envy anyone and always avoid useless conversation.” – Srimad Bhagavatam 11.10.6
“The guru and disciple should reside together for at least a year, testing each other before they decide to enter into a guru-disciple relationship. They should examine each other to find out their nature, character and compatibility.” Mantra Muktavalli
“A disciple must endeavour with his life, wealth and work for the favoured projects of the acarya and serve him with body, mind and words. In this way the disciple attains the highest spiritual good.” – Vishnu Smriti
“When a person obtains the mercy of his guru, he receives the Vaishnava mantra from him. By constantly chanting the mantra he inherits unimaginable opulence and ultimately the lotus feet of the Supreme Lord. Those who have performed immense pious deeds and austerities over many hundreds of years chant this mantra and thus are able to deliver the entire world.” – Agama Shastra
“When a person who has been properly chanting the Vaishnava mantra constantly for a long time glances on anyone, that person is instantly freed from the worst type of fear and anguish.” – Vishnu Purana