SB 7.8.1
sri-narada uvaca
atha daitya-sutah sarve
srutva tad-anuvarnitam
jagrhur niravadyatvan
naiva gurv-anusiksitam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Narada Muni continued: All the sons of the demons appreciated the transcendental instructions of Prahlada Maharaja and took them very seriously. They rejected the materialistic instructions given by their teachers, Sanda and Amarka.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
This is the effect of the preaching of a pure devotee like Prahlada Maharaja. If a devotee is qualified, sincere and serious about Krsna consciousness and if he follows the instructions of a bona fide spiritual master, as Prahlada Maharaja did when preaching the instructions he had received from Narada Muni, his preaching is effective. As it is said in the Srimad-Bhagavatam (3.25.25):
satam prasangan mama virya-samvido
bhavanti hrt-karna-rasayanah kathah
If one tries to understand the discourses given by the sat, or pure devotees, those instructions will be very pleasing to the ear and appealing to the heart. Thus if one is inspired to take to Krsna consciousness and if one practices the process in his life, he is surely successful in returning home, back to Godhead. By the grace of Prahlada Maharaja, all his class friends, the sons of the demons, became Vaisnavas. They did not like hearing from their so-called teachers Sanda and Amarka, who were interested only in teaching them about diplomacy, politics, economic development and similar topics meant exclusively for sense gratification.