Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 37
Sanskrit:
मैत्रेय उवाचऋग्यजु:सामाथर्वाख्यान् वेदान् पूर्वादिभिर्मुखै: ।शास्त्रमिज्यां स्तुतिस्तोमं प्रायश्चित्तं व्यधात्क्रमात् ॥ ३७ ॥
ITRANS:
maitreya uvācaṛg-yajuḥ-sāmātharvākhyānvedān pūrvādibhir mukhaiḥśāstram ijyāṁ stuti-stomaṁprāyaścittaṁ vyadhāt kramāt
Translation:
Maitreya said: Beginning from the front face of Brahmā, gradually the four Vedas — Ṛk, Yajur, Sāma and Atharva — became manifest. Thereafter, Vedic hymns which had not been pronounced before, priestly rituals, the subject matters of the recitation, and transcendental activities were all established, one after another.