Srimad Bhagavatam Canto 04, Chapter 27, Text 30

SB 4.27.30

prajvaro ’yam mama bhrata
 tvam ca me bhagini bhava
caramy ubhabhyam loke ’sminn
 avyakto bhima-sainikah
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The King of the Yavanas continued: Here is my brother Prajvara. I now accept you as my sister. I shall employ both of you, as well as my dangerous soldiers, to act imperceptibly within this world.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Kalakanya was sent by Narada Muni to Yavana-raja so that she might become his wife, but instead of accepting her as his wife, Yavana-raja accepted her as his sister. Those who do not follow the Vedic principles are unrestricted as far as sex life is concerned. Consequently they sometimes do not hesitate to have sex with their sisters. In this Age of Kali there are many instances of such incest. Although Yavana-raja accepted the request of Narada Muni to show respect to him, he was nonetheless thinking of illicit sex. This was due to his being the King of the yavanas and mlecchas.
 
The word prajvarah is very significant, for it means “the fever sent by Lord Visnu.” Such a fever is always set at 107 degrees, the temperature at which a man dies. Thus the King of the mlecchas and yavanas requested the daughter of Time, Kalakanya, to become his sister. There was no need to ask her to become his wife, for the yavanas and mlecchas do not make distinctions as far as sex life is concerned. Thus one may outwardly be a sister, mother or daughter and still have sex. Yavana-raja’s brother was Prajvara, and Kalakanya was invalidity itself. Combined and strengthened by the soldiers of Yavana-raja — namely nonhygienic conditions, illicit sex and ultimately a high degree of temperature to bring on death — they would be able to smash the materialistic way of life. In this connection it is significant that Narada was immune to the attack of jara, or invalidity. Similarly jara, or the destructive force, cannot attack any follower of Narada Muni or another pure Vaisnava.
 
Thus end the Bhaktivedanta purports of the Fourth Canto, Twenty-seventh Chapter, of the Srimad-Bhagavatam, entitled “Attack by Candavega on the City of King Purañjana; the Character of Kalakanya.”
Srimad Bhagavatam Canto 04, Chapter 27, Text 29
Srimad Bhagavatam Canto 04, Chapter 27 Overview