Shiva Purana
शैलो ददर्श तन्तत्र विष्णुरूपधरन्द्रुतम् ॥ ततो ब्रह्मस्वरूपं च सूर्य्यरूपं ततः क्षणात् ॥ ३० ॥
Immediately the mountain saw him assuming the form of Viṣṇu, then the form of Brahmā and in a trice that of the sun.
english translation
zailo dadarza tantatra viSNurUpadharandrutam ॥ tato brahmasvarUpaM ca sUryyarUpaM tataH kSaNAt ॥ 30 ॥
hk transliteration by Sanscript