PURPORT

It is also said that Vasudeva and Devaki both in their previous birth as Sutapah and Prishni underwent a severe type of penance to get the Lord as their son and as result of such austerities the Lord appeared as their son. That was only a source otherwise, as it is already declared in the Bhagwat Geeta, the Lord appeared for welfare of all people of the world and to vanquish the Asuras or the materialistic atheists.