SB 3.1.40
aho prthapi dhriyate ’rbhakarthe
rajarsi-varyena vinapi tena
yas tv eka-viro ’dhiratho vijigye
dhanur dvitiyah kakubhas catasrah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O my lord, is Prtha still living? She lived only for the sake of her fatherless children; otherwise it was impossible for her to live without King Pandu, who was the greatest commander and who alone conquered the four directions simply with the help of a second bow.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
A faithful wife cannot live without her lord, the husband, and therefore all widows used to voluntarily embrace the burning fire which consumed the dead husband. This system was very common in India because all the wives were chaste and faithful to their husbands. Later on, with the advent of the Age of Kali, the wives gradually began to be less adherent to their husbands, and the voluntary embrace of the fire by the widows became a thing of the past. Very recently the system was abolished, since the voluntary system had become a forcible social custom.
When Maharaja Pandu died, both his wives, namely Kunti and Madri, were prepared to embrace the fire, but Madri requested Kunti to live for the sake of the younger children, the five Pandavas. This was agreed upon by Kunti at the added request of Vyasadeva. In spite of her great bereavement, Kunti decided to live, not to enjoy life in the absence of her husband, but only to give protection to the children. This incident is referred to here by Vidura because he knew all the facts about his sister-in-law Kuntidevi. It is understood that Maharaja Pandu was a great warrior and that he alone, with the help of bow and arrow, could conquer the world’s four directions. In the absence of such a husband, it was almost impossible for Kunti to live on even as a widow, but she had to do it for the sake of the five children.