Srimad Bhagavatam Canto 03, Chapter 21, Text 01

SB 3.21.1

vidura uvaca
svayambhuvasya ca manor
 vamsah parama-sammatah
kathyatam bhagavan yatra
 maithunenaidhire prajah
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Vidura said: The line of Svayambhuva Manu was most esteemed. O worshipful sage, I beg you: Give me an account of this race, whose progeny multiplied through sexual intercourse.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Regulated sex life to generate good population is worth accepting. Actually, Vidura was not interested in hearing the history of persons who merely engaged in sex life, but he was interested in the progeny of Svayambhuva Manu because in that dynasty good devotee kings appeared who protected their subjects very carefully with spiritual knowledge. By hearing the history of their activities, therefore, one becomes more enlightened. An important word used in this connection is parama-sammatah, which indicates that the progeny created by Svayambhuva Manu and his sons was approved of by great authorities. In other words, sex life for creating exemplary population is acceptable to all sages and authorities of Vedic scripture.
Srimad Bhagavatam Canto 03, Chapter 21, Text 02