Srimad Bhagavatam Canto 07, Chapter 01, Text 35

SB 7.1.35

 etad akhyatum arhasi
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
The bodies of the inhabitants of Vaikuntha are completely spiritual, having nothing to do with the material body, senses or life air. Therefore, kindly explain how associates of the Personality of Godhead were cursed to descend in material bodies like ordinary persons.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
This very significant question would be difficult for an ordinary person to answer, but Narada Muni, being an authority, could answer it. Therefore Maharaja Yudhisthira inquired from him, saying, etad akhyatum arhasi: “Only you can explain the reason.” From authoritative sources it can be discerned that associates of Lord Visnu who descend from Vaikuntha do not actually fall. They come with the purpose of fulfilling the desire of the Lord, and their descent to this material world is comparable to that of the Lord. The Lord comes to this material world through the agency of His internal potency, and similarly, when a devotee or associate of the Lord descends to this material world, he does so through the action of the spiritual energy. Any pastime conducted by the Supreme Personality of Godhead is an arrangement by yoga-maya, not maha-maya. Therefore it is to be understood that when Jaya and Vijaya descended to this material world, they came because there was something to be done for the Supreme Personality of Godhead. Otherwise it is a fact that no one falls from Vaikuntha.
Of course, a living entity who desires sayujya-mukti remains in Krsna’s Brahman effulgence, which is dependent on Krsna’s body (brahmano hi pratisthaham). Such an impersonalist who takes shelter of the Brahman effulgence must surely fall down. This is stated in the sastra (Bhag. 10.2.32):
ye ’nye ’ravindaksa vimukta-maninas
 tvayy asta-bhavad avisuddha-buddhayah
aruhya krcchrena param padam tatah
 patanty adho ’nadrta-yusmad-anghrayah
“O Lord, the intelligence of those who think themselves liberated but who have no devotion is impure. Even though they rise to the highest point of liberation by dint of severe penances and austerities, they are sure to fall down again into material existence, for they do not take shelter at Your lotus feet.” The impersonalists cannot reach the Vaikuntha planets to become associates of the Lord, and therefore, according to their desires, Krsna gives them sayujya-mukti. However, since sayujya-mukti is partial mukti, they must fall again to this material world. When it is said that the individual soul falls from Brahmaloka, this applies to the impersonalist.
From authoritative sources it is learned that Jaya and Vijaya were sent to this material world to fulfill the Lord’s desire to fight. The Lord also sometimes wants to fight, but who can fight with the Lord but a very confidential devotee of the Lord? Jaya and Vijaya descended to this world to fulfill the Lord’s desire. Therefore in each of their three births — first as Hiranyaksa and Hiranyakasipu, second as Ravana and Kumbhakarna, and third as Sisupala and Dantavakra — the Lord personally killed them. In other words, these associates of the Lord, Jaya and Vijaya, descended to the material world to serve the Lord by fulfilling His desire to fight. Otherwise, as Maharaja Yudhisthira says, asraddheya ivabhati: the statement that a servant of the Lord could fall from Vaikuntha seems unbelievable. How Jaya and Vijaya came to this material world is explained by Narada Muni as follows.
Srimad Bhagavatam Canto 07, Chapter 01, Text 34
Srimad Bhagavatam Canto 07, Chapter 01, Text 36