Srimad Bhagavatam Canto 03, Chapter 09, Text 02

SB 3.9.2

rupam yad etad avabodha-rasodayena
 sasvan-nivrtta-tamasah sad-anugrahaya
adau grhitam avatara-sataika-bijam
 yan-nabhi-padma-bhavanad aham avirasam
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The form which I see is eternally freed from material contamination and has advented to show mercy to the devotees as a manifestation of internal potency. This incarnation is the origin of many other incarnations, and I am born from the lotus flower grown from Your navel home.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The three deities Brahma, Visnu and Mahesvara (Siva), the executive heads of the three modes of material nature (passion, goodness and ignorance), are all generated from Garbhodakasayi Visnu, who is described herein by Brahma. From the Ksirodakasayi Visnu, many Visnu incarnations expand at different ages in the duration of the cosmic manifestation. They are expanded only for the transcendental happiness of the pure devotees. The incarnations of Visnu, who appear at different ages and times, are never to be compared to the conditioned souls. The visnu-tattvas are not to be compared to deities like Brahma and Siva, nor are they on the same level. Anyone who compares them is called a pasandi, or infidel. Tamasah, mentioned herein, is the material nature, and the spiritual nature has a completely separate existence from tamah. Therefore, spiritual nature is called avabodha-rasa, or avarodha-rasa. Avarodha means “that which completely nullifies.” In the Transcendence there is no chance of material contact by any means. Brahma is the first living being, and therefore he mentions his birth from the lotus flower generated from the abdomen of Garbhodakasayi Visnu.
Srimad Bhagavatam Canto 03, Chapter 09, Text 01
Srimad Bhagavatam Canto 03, Chapter 09, Text 03