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.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
गन्धर्वानवधीत्तत्र वध्यान् वै विष्णुशक्तिधृक् । नागाल्लब्धवरः सर्पादभयं स्मरतामिदम्
gandharvānavadhīttatra vadhyān vai viṣṇuśaktidhṛk | nāgāllabdhavaraḥ sarpādabhayaṃ smaratāmidam
SB 9.7.3