Shiva Purana
आक्रान्तसप्तपातालकुहरोपि महाबलः ॥ प्राप्ते कलियुगे घोरे मृदुतामुपयास्यति ॥ ९ ॥
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