Srimad Bhagavatam Canto 03, Chapter 13, Text 11

SB 3.13.11

sa tvam asyam apatyani
 sadrsany atmano gunaih
utpadya sasa dharmena
 gam yajñaih purusam yaja
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Since you are my very obedient son, I ask you to beget children qualified like yourself in the womb of your wife. Rule the world in pursuance of the principles of devotional service unto the Supreme Personality of Godhead, and thus worship the Lord by performances of yajña.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The purpose of the material creation by Brahma is clearly described herein. Every human being should beget nice children in the womb of his wife, as a sacrifice for the purpose of worshiping the Supreme Personality of Godhead in devotional service. In the Visnu Purana (3.8.9) it is stated:
 
varnasramacaravata
 purusena parah puman
visnur aradhyate pantha
 nanyat tat-tosa-karanam
 
“One can worship the Supreme Personality of Godhead, Visnu, by proper discharge of the principles of varna and asrama. There is no alternative to pacifying the Lord by execution of the principles of the varnasrama system.”
 
Visnu worship is the ultimate aim of human life. Those who take the license of married life for sense enjoyment must also take the responsibility to satisfy the Supreme Personality of Godhead, Visnu, and the first stepping-stone is the varnasrama-dharma system. Varnasrama-dharma is the systematic institution for advancing in worship of Visnu. However, if one directly engages in the process of devotional service to the Supreme Personality of Godhead, it may not be necessary to undergo the disciplinary system of varnasrama-dharma. The other sons of Brahma, the Kumaras, directly engaged in devotional service, and thus they had no need to execute the principles of varnasrama-dharma.
Srimad Bhagavatam Canto 03, Chapter 13, Text 10
Srimad Bhagavatam Canto 03, Chapter 13, Text 12