Shiva Purana
शक्रमुद्दिश्य स मुनिस्तपस्तेपे सुदुः सहम् ॥ निश्चलात्मा शिलादाख्यो बहुकालं दृढव्रतः ॥ ५ ॥
That sage Śilāda performed a severe penance with Indra in view, for a long time. His mind was steady and he was stead-fast in his activities.
english translation
zakramuddizya sa munistapastepe suduH saham ॥ nizcalAtmA zilAdAkhyo bahukAlaM dRDhavrataH ॥ 5 ॥
hk transliteration by Sanscript