Shiva Purana
दृष्टो रुद्रेण देवो ऽसावसृजद्विश्वमीश्वरः ॥ वर्णाश्रमव्यवस्थां च चकार स पृथक्पृथक् ॥ ११ ॥
Brahmā viewed by Rudra created the universe. He prescribed the rules for different bastes and stages of life separately.
english translation
dRSTo rudreNa devo 'sAvasRjadvizvamIzvaraH ॥ varNAzramavyavasthAM ca cakAra sa pRthakpRthak ॥ 11 ॥
hk transliteration by Sanscript