Srimad Bhagavatam Canto 12, Chapter 02, Text 38

SB 12.2.38

tav ihaitya kaler ante
 vasudevanusiksitau
varnasrama-yutam dharmam
 purva-vat prathayisyatah
 
Translation: 
 
At the end of the Age of Kali, these two kings, having received instruction directly from the Supreme Personality of Godhead, Vasudeva, will return to human society and reestablish the eternal religion of man, characterized by the divisions of varna and asrama, just as it was before.
 
Purport: 
 
According to this and the previous verse, the two great kings who will reestablish human culture after the end of Kali-yuga have already descended to the earth, where they are patiently waiting to render their devotional service to Lord Visnu.
Srimad Bhagavatam Canto 12, Chapter 02, Text 37
Srimad Bhagavatam Canto 12, Chapter 02, Text 39