Srimad Bhagavatam Canto 03, Chapter 21, Text 05

SB 3.21.5

rucir yo bhagavan brahman
 dakso va brahmanah sutah
yatha sasarja bhutani
 labdhva bharyam ca manavim
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
O holy sage, tell me how the worshipful Ruci and Daksa, the son of Brahma, generated children after securing as their wives the other two daughters of Svayambhuva Manu.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
All the great personalities who increased the population in the beginning of the creation are called Prajapatis. Brahma is also known as Prajapati, as were some of his later sons. Svayambhuva Manu is also known as Prajapati, as is Daksa, another son of Brahma. Svayambhuva had two daughters, Akuti and Prasuti. The Prajapati Ruci married Akuti, and Daksa married Prasuti. These couples and their children produced immense numbers of children to populate the entire universe. Vidura’s inquiry was, “How did they beget the population in the beginning?”
Srimad Bhagavatam Canto 03, Chapter 21, Text 04
Srimad Bhagavatam Canto 03, Chapter 21, Text 06