Kansa, the King of Mathura, was Devki’s brother and Krishna’s uncle. He heard a prophecy that Devki’s eighth son will kill him. So, Kansa jailed his sister along with brother-in-law Vasudeva. He killed the first seven sons of Devki but destiny had its own story to unfold. Devki gave birth to Krishna and he’s taken to safety by Nand, who becomes his foster father. Later, a grown up Krishna avenges the humiliation of his real parents by killing Kansa, fulfilling the prophesy.
Painting, Akbarnama, Akbar's pilgrimage to Ajmer in thanksgiving for the birth of Prince Salim, outline by Basawan, painting by Nand Gwaliari, opaque watercolour and gold on paper, Mughal, ca. 1586-1589, Victoria and Albert Museum