SB 10.1.16
vasudeva-katha-prasnah
purusams trin punati hi
vaktaram pracchakam srotrms
tat-pada-salilam yatha
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The Ganges, emanating from the toe of Lord Visnu, purifies the three worlds, the upper, middle and lower planetary systems. Similarly, when one asks questions about the pastimes and characteristics of Lord Vasudeva, Krsna, three varieties of men are purified: the speaker or preacher, he who inquires, and the people in general who listen.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
It is said, tasmad gurum prapadyeta jijñasuh sreya uttamam (Bhag. 11.3.21). Those interested in understanding transcendental subject matters as the goal of life must approach the bona fide spiritual master. Tasmad gurum prapadyeta. One must surrender to such a guru, who can give right information about Krsna. Herein, Maharaja Pariksit has surrendered to the right personality, Sukadeva Gosvami, for enlightenment in vasudeva-katha. Vasudeva is the original Personality of Godhead, who has unlimited spiritual activities. Srimad-Bhagavatam is a record of such activities, and Bhagavad-gita is the record of Vasudeva speaking personally. Therefore, since the Krsna consciousness movement is full of vasudeva-katha, anyone who hears, anyone who joins the movement and anyone who preaches will be purified.