Shiva Purana
सर्वथा शिवरूपो हि रुद्रो रौद्रपराक्रमः॥ उत्पन्नो भक्तकार्यार्थं हरिब्रह्मसहायकृत् ॥ १२॥
Rudra of terrible exploits has the form of Śiva in every respect. He was born for carrying out the tasks of the devotees. He helps Viṣṇu and Brahmā.
english translation
sarvathA zivarUpo hi rudro raudraparAkramaH॥ utpanno bhaktakAryArthaM haribrahmasahAyakRt ॥ 12॥
hk transliteration by Sanscript