Reading Guide. This famous episode is a folktale inserted into the Mahabharata, with a mongoose as the storyteller! You will see a reference here to an "unchha vow" (Sanskrit unchha vrtti) which means living upon grains picked up from fields after the crops have been harvested.
Source. The Story of the Great War by Annie Besant (1899). [500 words]
Vast was the wealth expended in that sacrifice, the arches, ornamental stakes, jars and vessels being all of gold, and myriads of golden coins being given away. To Vyasa, the king gave the conquered earth as gift, declaring his wish to go away into the woods. But Vyasa bade him redeem the earth with gold, and he yielded to the command, and all who attended the sacrifice, from brahmins to mlechchas, returned home laden with wealth.
But a curious thing happened. A mongoose, half of whose body was golden, appeared and said, "Ye kings, this great sacrifice is not equal to a little measure of powdered barley given away by a liberal brahmin of Kurukshetra, who was observing the unccha vow."
Questioned as to the meaning of his strange words, the mongoose told the following story:
There was a brahmin who, with his family, was living on the grains of corn he could pick up in the fields, eating but once a day at a fixed hour. And behold! A terrible famine laid waste the land, and it chanced many times that at the meal time no food was to be had, and the man, his wife, his son and his daughter-in-law grew thin and weak, till they were mere living skeletons.
Now one day the brahmin picked up some barley, and, powdering it, they were about to sit down to eat it, having divided it into four portions. At that moment came a guest, and, welcoming him, they gave him water and a seat, and then the brahmin gave him his share of food. The guest ate it, but was still hungry, and the wife brought her share to her husband and prayed him to feed with it their guest. Seeing her shaking with the weakness of starvation, he gently bade her keep it, but she pleaded sweetly till he gave it, and still the guest's hunger was unappeased. Then the son brought his share, dutifully urging his claim to share his father's hunger, and the brahmin gave it smilingly to his hungry guest. Alas! He was still hungry, having eaten it, and what remained? Only the young wife's share, and that it broke her father's heart to give, the food of the tender child he loved so well. Yet her sacrifice was made with such grace of sweet humility that, blessing her, he took it and gave it to his guest, and lo, that guest arose in dazzling radiance of divinity, and it was Dharma whom they had fed.
And the God praised and blessed them, in that they had kept righteousness unstained, and bade them rise in happy peace to heaven. And the mongoose, coming where some grains of the barley-powder had fallen, rolled on them and half his body turned to gold from the magic power of that loving sacrifice, and ever after had he sought a sacrifice of equal merit and had found none, no, not that sacrifice of king Yudhishthira, with all its gorgeous profusion of gold and gems.