Shiva Purana

siva.sh/siva-purana/kotirudra-samhita/8/9

आक्रान्तसप्तपातालकुहरोपि महाबलः ।। प्राप्ते कलियुगे घोरे मृदुतामुपयास्यति ।। ९ ।।

sanskrit

Mahābala, though it has pervaded the regions as far below as the seven nether worlds, will become soft when the terrible age of Kali arrives.

english translation

AkrAntasaptapAtAlakuharopi mahAbalaH || prApte kaliyuge ghore mRdutAmupayAsyati || 9 ||

hk transliteration by Sanscript