Srimad-Bhagavatam: Canto 12 - Chapter 1 - Verse 44
Sanskrit:
तेनासौ चतुरो वेदांश्चतुर्भिर्वदनैर्विभु: ।सव्याहृतिकान् सोंकारांश्चातुर्होत्रविवक्षया ॥ ४४ ॥
ITRANS:
tenāsau caturo vedāṁścaturbhir vadanair vibhuḥsa-vyāhṛtikān soṁkārāṁścātur-hotra-vivakṣayā
Translation:
All-powerful Brahmā made use of this collection of sounds to produce from his four faces the four Vedas, which appeared together with the sacred oṁkāra and the seven vyāhṛti invocations. His intention was to propagate the process of Vedic sacrifice according to the different functions performed by the priests of each of the four Vedas.