Srimad Bhagavatam Canto 09, Chapter 14, Text 02

SB 9.14.2

sahasra-sirasah pumso
 nabhi-hrada-saroruhat
jatasyasit suto dhatur
 atrih pitr-samo gunaih
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Lord Visnu [Garbhodakasayi Visnu] is also known as Sahasra-sirsa Purusa. From the lake of His navel sprang a lotus, on which Lord Brahma was generated. Atri, the son of Lord Brahma, was as qualified as his father.
Srimad Bhagavatam Canto 09, Chapter 14, Text 01
Srimad Bhagavatam Canto 09, Chapter 14, Text 03