I'm finding Source for "VishvAdhiko Rudro Maharshi" Mantra.
विश्वाधिको रुद्रो महर्षिः
VishvAdhiko Rudro Maharshi
Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.Visit Stack Exchange
Hinduism Stack Exchange is a question and answer site for followers of the Hindu religion and those interested in learning more about Hinduism. It only takes a minute to sign up.Sign up to join this community
Taittariya Aranyaka of Krishna Yajurveda (10.12) contains this mantra:
यो देवानां प्रथमं पुरस्ताद्विश्वाधिको रुद्रो महर्षिः ।
हिरण्यगर्भं पश्यत जायमानꣳ स नो देवः शुभयास्मृत्या संयुनक्तु ॥ (Taittariya Aranyaka 10.12)
This mantra is also quoted in Shwetashwatara Upanishad 3.4 with slight variation:
यो देवानां प्रभवश्चोद्भवश्च विश्वाधिपो रुद्रो महर्षिः ।
हिरण्यगर्भं जनयामास पूर्वंस नो बुद्ध्या शुभया संयुनक्तु ॥ ४॥
He, the omniscient Rudra, the creator of the gods and the bestower of their powers, the support of the universe, He who, in the beginning, gave birth to Hiranyagarbha-may He endow us with clear intellect!
Similarly, in Bhasma Jabala Upanishad also Lord Shiva speaks:
विश्वं भूतं भुवनं चित्रं बहुधा जातं जायमानं च यत्सर्वस्य सोमोऽहमेव जनिता विश्वाधिको रुद्रो महर्षिः । (Bhasma Jabala Upanishad)
I, Soma, am the creator of various worlds, past, present, and future. I, Rudra the great seer transcending all, see the Brahma and other created beings.