Bheeshma requested sage pulastya how Marudganas born immortal and came into existance . In both padma purana and vishnu purana they mentioned about Diti’s revenge to kill Indra which made her children immortal with her severe penance and following Pournamasi Vrat.
Diti’s severe penance over the death of her children
Diti is Sage Kashyap’s wife. All children and grandchildren of Diti were killed in a war between deities and demons. Diti’s grief made her to take revenge and did penance for 100 divine years at the bank of saraswathi river.
Sage kashyap arrived there and asked for the boon. Diti asked for the son who could kill King Indra. Sage Kashyap agreed to the Diti’s wish and granted her a boon and explained some conditions to her till she delivers a child and he left to Udaygiri mountain to continue his penance. She continued to stay in the same place where she did the penance. Indra who came to know about the news was waiting for the chance when Diti disobeys any of the conditions Kashyap described so he can destroy the fetus. So Indra was roaming around her hermitage in disguise for about 99 years.
Diti performs Pournamasi Vrat
Once Diti three days prior to her delivery, after attending her natures call, forgets to wash her feet, goes to bed and soon fell a sleep with her head stooping down and opened hair as she is tired. Indra found the opportune moment, went inside her womb through the nostrils and cut the fetus into 7 pieces. each fragment transformed into infant and started crying loudly. Frustrated Indra cut each infant once again into 7 pieces. Immediately 49 babies emerged crying loudly. Terrified Indra started shouting ” Marud”, ” Marud ” meaning stop crying. Indra realized this is happening because all these years she was doing ‘pournimasi vrat’ which made them immortal. So indra apologized Diti and took 49 infants and Diti to Indra loka. In-spite of being Demons those 49 Marudganas never mingled with Demons and was virtuous.