Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 45
Sanskrit:
तस्योष्णिगासील्लोमभ्यो गायत्री च त्वचो विभो: ।त्रिष्टुम्मांसात्स्नुतोऽनुष्टुब्जगत्यस्थ्न: प्रजापते: ॥ ४५ ॥
ITRANS:
tasyoṣṇig āsīl lomabhyogāyatrī ca tvaco vibhoḥtriṣṭum māṁsāt snuto ’nuṣṭubjagaty asthnaḥ prajāpateḥ
Translation:
Thereafter the art of literary expression, uṣṇik, was generated from the hairs on the body of the almighty Prajāpati. The principal Vedic hymn, gāyatrī, was generated from the skin, triṣṭup from the flesh, anuṣṭup from the veins, and jagatī from the bones of the lord of the living entities.