Skandapurana 5.113.74

5.113.74

taṃ śrutvā ye na yāsyaṃti pātālaṃ pannagādhamāḥ ..
yuṣmadvākyādbhaviṣyaṃti nirviṣāste na saṃśayaḥ .. 74 .. ..

Those vilest of serpents who, having heard it, do not go to Pātāla, / will become venomless on your word; of this there is no doubt.”