Ramayana
ददृशाते तु तौ तत्र दरीं दशरथात्मजौ । पातालसमगम्भीरां तमसा नित्यसंवृताम् ॥ ३-६९-१०
Both the sons of Dasaratha, saw there a cave perpetually enveloped in darkness which was as deep as the netherworld. ॥ 3-69-10॥
english translation
dadRzAte tu tau tatra darIM dazarathAtmajau । pAtAlasamagambhIrAM tamasA nityasaMvRtAm ॥ 3-69-10
hk transliteration by Sanscript