sa vai sat-karmaṇāṁ sākṣād dvijāter iha sambhavaḥ
sa vai sat-karmaṇāṁ sākṣād dvijāter iha sambhavaḥ |
ādyo’ṅga yatrāśramiṇāṁ yathāhaṁ jñānado guruḥ ||
(Śrīmad Bhāgavatam: 10.80.32)
“[Kṛṣṇa to Sudāma:] Here he because of whom existence arises [i.e., one’s father] is the first guru, he because of whom [the existence] of a twice-born’s meritorious activities arises is [the second guru] like I [myself], and he who is a giver of knowledge to the members of the āśramas is [the third guru] directly [I myself].”