Srimad-Bhagavatam: Canto 5 - Chapter 1 - Verse 30
Sanskrit:
ततोऽधस्ताद्रसातले दैतेया दानवा: पणयो नाम निवातकवचा: कालेया हिरण्यपुरवासिन इति विबुधप्रत्यनीका उत्पत्त्या महौजसो महासाहसिनो भगवत: सकललोकानुभावस्य हरेरेव तेजसा प्रतिहतबलावलेपा बिलेशया इव वसन्ति ये वै सरमयेन्द्रदूत्या वाग्भिर्मन्त्रवर्णाभिरिन्द्राद्बिभ्यति ॥ ३० ॥
ITRANS:
tato ’dhastād rasātale daiteyā dānavāḥ paṇayo nāma nivāta-kavacāḥ kāleyā hiraṇya-puravāsina iti vibudha-pratyanīkā utpattyā mahaujaso mahā-sāhasino bhagavataḥ sakala-lokānubhāvasya harer eva tejasā pratihata-balāvalepā bileśayā iva vasanti ye vai saramayendra-dūtyā vāgbhir mantra-varṇābhir indrād bibhyati.
Translation:
Beneath Mahātala is the planetary system known as Rasātala, which is the abode of the demoniac sons of Diti and Danu. They are called Paṇis, Nivāta-kavacas, Kāleyas and Hiraṇya-puravāsīs [those living in Hiraṇya-pura]. They are all enemies of the demigods, and they reside in holes like snakes. From birth they are extremely powerful and cruel, and although they are proud of their strength, they are always defeated by the Sudarśana cakra of the Supreme Personality of Godhead, who rules all the planetary systems. When a female messenger from Indra named Saramā chants a particular curse, the serpentine demons of Mahātala become very afraid of Indra.
Purport:
It is said that there was a great fight between these serpentine demons and Indra, the King of heaven. When the defeated demons met the female messenger Saramā, who was chanting a mantra, they became afraid, and therefore they are living in the planet called Rasātala.