Srimad Bhagavatam Canto 10, Chapter 03, Text 40

SB 10.3.40

gate mayi yuvam labdhva
 varam mat-sadrsam sutam
gramyan bhogan abhuñjatham
 yuvam prapta-manorathau
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
After you received that benediction and I disappeared, you engaged yourselves in sex to have a son like Me, and I fulfilled your desire.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
According to the Sanskrit dictionary Amara-kosa, sex life is also called gramya-dharma, material desire, but in spiritual life this gramya-dharma, the material desire for sex, is not very much appreciated. If one has a tinge of attachment for the material enjoyments of eating, sleeping, mating and defending, one is not niskiñcana. But one really should be niskiñcana. Therefore, one should be free from the desire to beget a child like Krsna by sexual enjoyment. This is indirectly hinted at in this verse.
Srimad Bhagavatam Canto 10, Chapter 03, Text 39
Srimad Bhagavatam Canto 10, Chapter 03, Text 41