Caitanya-Caritamrta Adi 12.9
'Some of the disciples strictly accepted the orders of the acarya, and others deviated, independently concocting their own opinions under the spell of daivi-maya.'
"This verse describes the beginning of a schism. When disciples do not stick to the principle of accepting the order of their spiritual master, immediately there are two opinions. Any opinion different from the opinion of the spiritual master is useless. One cannot infiltrate materially concocted ideas into spiritual advancement. That is deviation. There is no scope for adjusting spiritual advancement to material ideas."
"The order of the spiritual master is the active principle in spiritual life. Anyone who disobeys the order of the spiritual master immediately becomes useless."
(Sri Caitanya-caritamrta, Adi-lila 12.8-10)
"The instructions received from the spiritual master must be followed immediately. One should not deviate from or surpass the instructions of the spiritual master."
(Srimad-Bhagavatam 5.5.14, purport)
"Brahma praises Kardama because he carried out the orders of the spiritual master in toto and without cheating [....] To honor the spiritual master means to carry out his instructions word for word." (Srimad-Bhagavatam 3.24.12, purport)
"Srila Visvanatha Cakravarti also advises that if we want to be successful in our attempt to go back to Godhead, we must very seriously act according to the instruction of the spiritual master. That is the way of perfection. There need be no anxiety over attaining perfection because if one follows the instruction given by the spiritual master he is sure to attain perfection. Our only concern should be how to execute the order of the spiritual master." (Srimad-Bhagavatam 4.8.71, purport)
"We have to render service to a guru and surrender ourselves. It is not that one should accept just any person as a guru. The guru must be the representative of Krsna; then one can surrender oneself. Surrender means that one will accept whatever the guru says. It is not that one thinks, "I do not care for my guru's order. Still I am a disciple." That is not actually accepting a guru. Of course, it has become a fashion to accept a guru in this way, but this will not help anyone." (Teachings of Lord Kapila)
"There should be no instance in which the disciple or the son says, "This is not correct. I cannot carry it out." When he says that, he is fallen […] the order of the spiritual master is the life and soul of the disciples." (Srimad-Bhagavatam 3.24.13, purport)
"This acceptance of the words of the spiritual master is called srauta-vakya, which indicates that the disciple must carry out the spiritual master's instructions without deviation. Srila Visvanatha Cakravarti Thakura remarks in this connection that a disciple must accept the words of his spiritual master as his life and soul." (Sri Caitanya-caritamrta, Adi-lila 7.72, 77, purport)
"The disciple must stick to whatever the spiritual master orders. Simply by following on that line, one sees the Supreme Personality of Godhead […] Instead of being eager to see the Lord in some bush in Vrndavana while at the same time engaging in sense gratification, if one instead sticks to the principle of following the words of the spiritual master, he will see the Supreme Lord without difficulty." (Bhagavatam 4.28.51, purport)
"As soon as the disciple thinks independently, not caring for the instructions of the spiritual master, he is a failure ." (Srimad-Bhagavatam 8.17.1, purport)