Srimad Bhagavatam Canto 03, Chapter 08, Text 16

SB 3.8.16

tasyam sa cambho-ruha-karnikayam
 avasthito lokam apasyamanah
parikraman vyomni vivrtta-netras
 catvari lebhe ’nudisam mukhani
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Brahma, born out of the lotus flower, could not see the world, although he was situated in the whorl. He therefore circumambulated all of space, and while moving his eyes in all directions he achieved four heads in terms of the four directions.
Srimad Bhagavatam Canto 03, Chapter 08, Text 15
Srimad Bhagavatam Canto 03, Chapter 08, Text 17