When Devaki heard about Sri Krishna bringing the dead son of Guru Sandeepany back to life, she wished to see her six dead sons, who were killed by Kamsa in prison before the birth of Krishna.
One day, Devaki approached Krishna and expressed her desire to see her first six sons who were killed by Kamsa. Sri Krishna and Balaram promised her that she will have a vision of her dead six sons.
Krishna and Balarama entered the region Sutala by their yogic powers and requested Mahabali who was ruling that region to release the six children temporarily, for comforting their mother, Devaki.
The children were brought and shown to Devaki. She was consoled by the vision of her children.