Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 44
Sanskrit:
आन्वीक्षिकी त्रयी वार्ता दण्डनीतिस्तथैव च ।एवं व्याहृतयश्वासन् प्रणवो ह्यस्य दहृत: ॥ ४४ ॥
ITRANS:
ānvīkṣikī trayī vārtādaṇḍa-nītis tathaiva caevaṁ vyāhṛtayaś cāsanpraṇavo hy asya dahrataḥ
Translation:
The science of logical argument, the Vedic goals of life, and also law and order, moral codes and the celebrated hymns bhūḥ, bhuvaḥ and svaḥ all became manifested from the mouths of Brahmā, and the praṇava oṁkāra was manifested from his heart.