SB 10.80.34
naham ijya-prajatibhyam
tapasopasamena va
tusyeyam sarva-bhutatma
guru-susrusaya yatha
Translation:
I, the Soul of all beings, am not as satisfied by ritual worship, brahminical initiation, penances or self-discipline as I am by faithful service rendered to one’s spiritual master.
Purport:
The word prajati here indicates either begetting good children or the second birth obtained by ritual initiation into Vedic culture. Although both of these are praiseworthy, Lord Krsna here states that faithful service rendered to a bona fide spiritual master is still higher.