Shiva Purana
स कथं भगवान् रुद्र आदिदेवः पुरातनः ॥ पुत्रत्वमगमच्छंभुर्ब्रह्मणो ऽव्यक्तजन्मनः ॥ ६ ॥
How is that ancient Lord Rudra, the original demigod? Lord Śambhu became the son of the unmanifest Brahman.
english translation
sa kathaM bhagavAn rudra AdidevaH purAtanaH ॥ putratvamagamacchaMbhurbrahmaNo 'vyaktajanmanaH ॥ 6 ॥
hk transliteration by Sanscript