Śrīmad-Bhāgavatam · Text 9.7.3
Who is speaking and story frame
गन्धर्वानवधीत् तत्र वध्यान् वै विष्णुशक्तिधृक् ।
नागाल्लब्धवर: सर्पादभयं स्मरतामिदम् ॥ ३ ॥
gandharvān avadhīt tatra
vadhyān vai viṣṇu-śakti-dhṛk
nāgāl labdha-varaḥ sarpād
abhayaṁ smaratām idam
There in Rasātala, the lower region of the universe, Purukutsa, being empowered by Lord Viṣṇu, was able to kill all the Gandharvas who deserved to be killed. Purukutsa received the benediction from the serpents that anyone who remembers this history of his being brought by Narmadā to the lower region of the universe will be assured of safety from the attack of snakes.
Read this verse on Vedabase.ioThis verse has no purport; its meaning is explained by the verses around it.