Srimad Bhagavatam Canto 03, Chapter 13, Text 23

SB 3.13.23

iti mimamsatas tasya
 brahmanah saha sunubhih
bhagavan yajña-puruso
 jagarjagendra-sannibhah
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
While Brahma was deliberating with his sons, the Supreme Personality of Godhead, Visnu, roared tumultuously like a great mountain.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
It appears that great hills and mountains also have their roaring power because they are also living entities. The volume of the sound vibrated is in proportion to the size of the material body. While Brahma was guessing about the appearance of the Lord’s incarnation as a boar, the Lord confirmed Brahma’s contemplation by roaring with His gorgeous voice.
Srimad Bhagavatam Canto 03, Chapter 13, Text 22
Srimad Bhagavatam Canto 03, Chapter 13, Text 24