The divine birth
There came a time when Mother Earth was unable to bear the sins and cruelty committed by evil kings and rulers. Mother Earth then prayed to Lord Brahma, the creator of the Universe, to relieve her from these sinful kings. Lord Brahma prayed to the supreme Lord Vishnu for reincarnation and to relieve the Mother Earth from these evil rulers. Lord Vishnu accepted the request and assured to defeat tyrannical forces.
The ruler of Mathura, Kansa was one such evil king. He had a sister named Devaki, who was married to Vasudeva. The day Devaki and Vasudeva got married, a voice from the sky forecasted that Devaki's eighth son will bring an end to Kansa's rule and will kill him.
Frightened Kansa held the couple. He then vowed that he will kill every child of Devaki and Vasudeva. Seeing their first seven children being killed by the cruel Kansa, the imprisoned couple feared giving birth to their eighth child.