Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 14

Sanskrit:

श्रीशुक उवाचएवं सङ्कीर्तित: कृष्णो मघोना भगवानमुम् । मेघगम्भीरया वाचा प्रहसन्निदमब्रवीत् ॥ १४ ॥

ITRANS:

śrī-śuka uvācaevaṁ saṅkīrtitaḥ kṛṣṇomaghonā bhagavān amummegha-gambhīrayā vācāprahasann idam abravīt

Translation:

Śukadeva Gosvāmī said: Thus glorified by Indra, Lord Kṛṣṇa, the Supreme Personality of Godhead, smiled and then spoke to him as follows in a voice resonant like the clouds.

Purport:

Although in this pastime Lord Kṛṣṇa appeared to be a small boy, the words megha-gambhīrayā vācā indicate that He spoke to Indra with the deep, resonant voice of the Supreme Lord.