Srimad Bhagavatam Canto 06, Chapter 04, Text 52

SB 6.4.52

mithuna-vyavaya-dharmas tvam
 praja-sargam imam punah
 bhuriso bhavayisyasi
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Now unite in sexual life as man and woman, and in this way, by sexual intercourse, you will be able to beget hundreds of children in the womb of this girl to increase the population.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
The Lord says in Bhagavad-gita (7.11), dharmaviruddho bhutesu kamo ’smi: “I am sex that is not contrary to religious principles.” Sexual intercourse ordained by the Supreme Personality of Godhead is dharma, a religious principle, but it is not intended for sense enjoyment. Indulgence in sense enjoyment through sexual intercourse is not allowed by the Vedic principles. One may follow the natural tendency for sex life only to beget children. Therefore the Lord told Daksa in this verse, “This girl is offered to you only for sex life to beget children, not for any other purpose. She is very fertile, and therefore you will be able to have as many children as you can beget.”
Srila Visvanatha Cakravarti Thakura remarks in this connection that Daksa was given the facility for unlimited sexual intercourse. In Daksa’s previous life he was also known as Daksa, but in the course of performing sacrifices he offended Lord Siva, and thus his head was replaced with that of a goat. Then Daksa gave up his life because of his degraded condition, but because he maintained the same unlimited sexual desires, he underwent austerities by which he satisfied the Supreme Lord, who then gave him unlimited potency for sexual intercourse.
It should be noted that although such a facility for sexual intercourse is achieved by the grace of the Supreme Personality of Godhead, this facility is not offered to advanced devotees, who are free from material desires (anyabhilasita-sunyam). In this connection it may be noted that if the American boys and girls engaged in the Krsna consciousness movement want to advance in Krsna consciousness to achieve the supreme benefit of loving service to the Lord, they should refrain from indulging in this facility for sex life. Therefore we advise that one should at least refrain from illicit sex. Even if there are opportunities for sex life, one should voluntarily accept the limitation of having sex only for progeny, not for any other purpose. Kardama Muni was also given the facility for sex life, but he had only a slight desire for it. Therefore after begetting children in the womb of Devahuti, Kardama Muni became completely renounced. The purport is that if one wants to return home, back to Godhead, one should voluntarily refrain from sex life. Sex should be accepted only as much as needed, not unlimitedly.
One should not think that Daksa received the favor of the Lord by receiving the facilities for unlimited sex. Later verses will reveal that Daksa again committed an offense, this time at the lotus feet of Narada. Therefore although sex life is the topmost enjoyment in the material world and although one may have an opportunity for sexual enjoyment by the grace of God, this entails a risk of committing offenses. Daksa was open to such offenses, and therefore, strictly speaking, he was not actually favored by the Supreme Lord. One should not seek the favor of the Lord for unlimited potency in sex life.
Srimad Bhagavatam Canto 06, Chapter 04, Text 51
Srimad Bhagavatam Canto 06, Chapter 04, Text 53