It is said at many place in Mahabharata:“ Yato Dharma tatah Krishna, Yatah Krishna Tato Jaya” Meaning..where there is righteousness, there is Krishna & where there is Krishna, there is Victory” Shri Krishna employed honest actions throughout his tenure on earth. He was completely truthful. When Ashwatthama released Brahmsheer Astra into Uttara's Womb, She was saved by Krishna, who was the maternal uncle of Abhimanyu. But, the fetus inside the womb died. When Sri Krishna, Balarama and Yadavas were busy visiting the inner chambers of Dhritarashtra and Gandhari. They met Mother Kunti. Subhadra sought the blessings of Kunti. Vidura and Yuyutsu made arrangements for the comfortable stay of Sri Krishna and Balarama and other Yadavas. Meanwhile, Uttara, wife of Abhimanyu, who was pregnant even at the time of killing of Abhimanyu, delivered a Stillborn child (A child who died in womb). When Shri Krishna came to know about this. He immediately proceeded to Kunti, along with his brothers. Kunti, Draupadi and Subhadra were lamenting loudly for the death of the child.
Kunti, with choked voice, Requested Krishna in following manner ““O Krishna! Except you, none else are there to save us. Look at that child. He is son of Abhimanyu, your sister’s son. But he is born dead. It is only due to the Brahma Sironamaka Astra (hereinafter called Brahma Astra) launched by Ashwatthama. With the influence of Brahma Astra, the child is dead even in womb of Uttara. You have to save that child. Have you forgotten the promise made while Ashwatthama launched Brahma Astra. You promised you will protect the child in the womb of Uttara. Krishna! our lives are in your hands. If the child is alive, we will survive. Otherwise, we have to die. If this child is not alive, none will remain in Pandava clan to offer Pindas and water to Pitaras. Hence you have to give life to this child and eradicate the grief of Uttara. O Krishna! you have been always protecting the Pandavas all the while. This child is the only survivor of Pandava clan. Hence give him life and protect Pandava Clan.” prayed Kunti.
Now Subhadra prayed his brother Krishna thus: “O Krishna! my beloved brother! To please Syodhana, Ashwatthama launched Brahma Astra. Now sufferers are myself and my husband, Arjuna. We lost the only survivor of Pandava clan. Arjuna is still lamenting in his inner self, remembering his son, Abhimanyu. Now Abimanyu’s son also is dead. Imagine the fate of Arjuna and his brothers, Dharmaja, Bhima, Nakula and Sahadeva. O brother Krishna! have you forgotten your promise that you will nullify the Brahma Astra launched by Ashwatthama and we were consoled with your words. But your promise is not fructified. Now it is time to save the child. I do not think that Pandavas will be defeated while you are alive. But, in your very presence, Ashwatthama destroyed the only survivor of Pandava clan. O Protector of your Devotees! I know that you alone are capable of restoring life to those who are dead. Now the grandson of your brother in law, your friend, your heart, is lying dead in front of you. Will you keep quiet. Kindly restore life to this child.” prayed Subhadra.
Krishna’s mind melted with the words of Kunti and Subhadra. “Dont worry. I will try my level best to restore life to the child” promised Krishna. Along with Kunti, Subhadra Krishna went to the labour room. Subhadra went near Uttara and woke her up.
Uttara after seeing that Lord Krishna has visited her she prayed to him with great hope & said “O God Krishna !All are aware that you always protect your devotees. Why cannot you shower your kindness and blessings towards me and bring back the life of this child. I lost my husband in war. Now I lost my child also. How can I survive without husband and child. O Krishna! has Ashwatthama got the capacity to kill the son of your own nephew? I would have followed my husband by burning myself on his pyre. As I was pregnant then, I could not follow my husband. Now I cannot live without my son. If I go to heaven, my husband may ask about my child. What would be my reply? Had I known on that day that I would be deprived of my child today, I would have followed my husband. I thought of showing my child to Sri Krishna with great joy. That cruel Ashwatthama made my joy futile.” lamented Uttara keeping the dead body of the child on his lap. She is waking up the child... “O my love! get up. your grandfather Sri Krishna has come. Get up and salute him. Is it proper to sleep while elders visit you.” so lamenting Uttara fell on the ground.
Beholding the grief of Uttara, everybody present there were weeping, showering tears from their eyes. Sri Krishna tried to console Uttara.
“O Uttara! don’t worry. I will bring back the life of your son.” promised Krishna. Krishna washed his feet and performed Achamanam. He sat down on a plank. Closed his eyes. Opened his inner eye. With his strong will, he nullified the Brahmasheera Astra launched by Ashwatthama. Then Shri Krishna, with concentrated will and mind made the following promises :
If I do not lie even with my enemy, if I do not turn my foot even in a dreadful war, this child will be alive.
If I do not feel any grudge in my mind towards anyone at any point of time, this child will be alive.
If it is true that I killed Kamsa and others only to restablish dharma (Righteouness), and if those killings of demons are acceptable to wise and learned, this child will be alive.
If I follow truth, Dharma and Brahmacharya always, this child will be alive.” promised Shri Krishna with highly concentrated mind.
With those promises, there was a movement in the child. He was moving his legs and hands. The child slowly opened his eyes and smiled. Beholding this Kunti, Draupadi, Subhadra’s joy knew no bounds. Their eyes were filled with joyful tears. Their bodies trembled. The hair on their body erected. Everybody there acclaimed with great joy. On hearing the joyful utterances, Uttara regained consciousness and saw the child playing by moving his hands and legs vigorously and smiling with joy. She could not control her joy. She took the child into her arms and rushed before Sri Krishna. She fell on the feet of Sri Krishna. Krishna lifted her and wiped her tears. Sri Krishna proclaimed, to the hearing of one and all, loudly : At the moment when everybody thought that the entire Pandava clan came to end, this child is reborn. Hence he is named as Parikshit, i.e. the one who has been tested, when he was in his mother's womb.