Srimad Bhagavatam Canto 10, Chapter 80, Text 32

SB 10.80.32

sa vai sat-karmanam saksad
 dvijater iha sambhavah
adyo ’nga yatrasraminam
 yathaham jñana-do guruh
 
Translation: 
 
My dear friend, he who gives a person his physical birth is his first spiritual master, and he who initiates him as a twice-born brahmana and engages him in religious duties is indeed more directly his spiritual master. But the person who bestows transcendental knowledge upon the members of all the spiritual orders of society is one’s ultimate spiritual master. Indeed, he is as good as My own self.
Srimad Bhagavatam Canto 10, Chapter 80, Text 31
Srimad Bhagavatam Canto 10, Chapter 80, Text 33