Shiva Purana
नन्दीश्वर उवाच ॥ ततो वृषभरूपेण गर्जमानः पिनाकधृक् ॥ प्रविष्टो विवरं तत्र निनदन्भैरवान्रवान् ॥ १ ॥
Nandīśvara said:- Then bellowing in the form of a Bull (Vṛṣabha), the Pināka-bearing lord entered the crevice and shouted terribly.
english translation
nandIzvara uvAca ॥ tato vRSabharUpeNa garjamAnaH pinAkadhRk ॥ praviSTo vivaraM tatra ninadanbhairavAnravAn ॥ 1 ॥
hk transliteration by Sanscript