Srimad-Bhagavatam: Canto 12 - Chapter 1 - Verse 37

Sanskrit:

सूत उवाचसमाहितात्मनो ब्रह्मन् ब्रह्मण: परमेष्ठिन: ।हृद्याकाशादभून्नादो वृत्तिरोधाद् विभाव्यते ॥ ३७ ॥

ITRANS:

sūta uvācasamāhitātmano brahmanbrahmaṇaḥ parameṣṭhinaḥhṛdy ākāśād abhūn nādovṛtti-rodhād vibhāvyate

Translation:

Sūta Gosvāmī said: O brāhmaṇa, first the subtle vibration of transcendental sound appeared from the sky of the heart of the most elevated Lord Brahmā, whose mind was perfectly fixed in spiritual realization. One can perceive this subtle vibration when one stops all external hearing.

Purport:

Because Śrīmad-Bhāgavatam is the supreme Vedic literature, the sages headed by Śaunaka desired to trace out its source.