SB 8.16.24
sri-kasyapa uvaca
etan me bhagavan prstah
praja-kamasya padmajah
yad aha te pravaksyami
vratam kesava-tosanam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Sri Kasyapa Muni said: When I desired offspring, I placed inquiries before Lord Brahma, who is born from a lotus flower. Now I shall explain to you the same process Lord Brahma instructed me, by which Kesava, the Supreme Personality of Godhead, is satisfied.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Here the process of devotional service is further explained. Kasyapa Muni wanted to instruct Aditi in the same process recommended to him by Brahma for satisfying the Supreme Personality of Godhead. This is valuable. The guru does not manufacture a new process to instruct the disciple. The disciple receives from the guru an authorized process received by the guru from his guru. This is called the system of disciplic succession (evam parampara-praptam imam rajarsayo viduh). This is the bona fide Vedic system of receiving the process of devotional service, by which the Supreme Personality of Godhead is pleased. Therefore, to approach a bona fide guru, or spiritual master, is essential. The bona fide spiritual master is he who has received the mercy of his guru, who in turn is bona fide because he has received the mercy of his guru. This is called the parampara system. Unless one follows this parampara system, the mantra one receives will be chanted for no purpose. Nowadays there are so many rascal gurus who manufacture their mantras as a process for material advancement, not spiritual advancement. Still, the mantra cannot be successful if it is manufactured. Mantras and the process of devotional service have special power, provided they are received from the authorized person.