The story of Blue-Eyed Mongoose at Yudhisthira's Ashwamedha Sacrifice is told in detail in Mahabharata - Book 14-Anugita Parva -Chapter 90 . Here the Mongoose is telling us the story of how half of his body turned Golden , just by eating a tiny bit of grain which was given in charity by a kurukshetra Brahmin , but this does not happen in this sacrifice. Thus he wanted to tell the Brahmanas and other people gathered there that " not only mere grand sacrifices and gifts and all grand sacrificial procession can give you the desired merit but a charitable gift of small powder of Barley is also sufficient . Many thousand Yogis and Rishis attained divine lokas by their "Tapas" alone , and not by sacrificial ceremonies alone.
Here is Brief Story as told in Mahabharata.- A blue eyed mongoose who's half body consists of gold enters at the site of Ashwamedha Yajna of yudhisthira and tells the assembled people there thus.
Vaisampayana said, 'Hear, O chief of kings of a most wonderful
incident that occurred, O puissant monarch, at the conclusion of that
great horse-sacrifice. After all the foremost of Brahmanas and all the
kinsmen and relatives and friends, and all the poor, the blind, and
the helpless ones had been gratified, O chief of Bharata's race, when
the gifts made in profusion were being spoken of on all sides, indeed,
when flowers were rained down on the head of king Yudhishthira the
just, a blue-eyed mongoose, O sinless one, with one side of his body
changed into gold, came there and spoke in a voice that was as loud
and deep as thunder. Repeatedly uttering such deep sounds and thereby
frightening all animals and birds, that proud denizen of a hole, with
large body, spoke in a human voice and said, 'Ye kings, this great
sacrifice is not equal to a prastha of powdered barley given away by a
liberal Brahmana of Kurukshetra who was observing the Unccha vow.'
Hearing these words of the mongoose, O king, all those foremost of
Brahmanas became filled with wonder. Approaching the mongoose, they
then asked him, saying,
Then the Brahmins assembled at Ashwamedha Sacrifice were surprised asked that blue eyed Mangoose questions about Who is he & his authority to say bad words about this Yajna , his knowledge of scriptures . Then they told the Mangoose that they have conducted the yajna according to injunctions , every rule was followed correctly and with according to justice . A whole lot of gifts were distributed to all of the people , ancestors are satisfied through Shradha here. And inspite this flawless procedure what you have seen in here that you are saying that "this great sacrifice is not equal to a prastha of powdered barley given away by a liberal Brahmana "
And upon enquiring thus the blue eyed mangoose told the story of Kurukshetra Brahmana gaining excellent fruit of a very little measure (of powdered barley) obtained by lawful means and by observance of what is called the "Unccha vow."
The story told by Mongoose is below.
Once, a great and dreadful famine occurred in Kurukshetra. Brahmanas engaged in Tapas some how managed to pass time of that difficult famine. One day that Brahmana , after the sixth division of food came, succeeded in obtaining a prastha of barley which then he powered , which called "Satu" .
Then they sat down to eat that barley , meantime there came unto their abode a guest Brahman . That Brahman who was observing Unccha vow gave his share of food to that guest , but the guest was not satisfied by mere few grains powdered . Upon seening this that Brahman also offered his wife's share to the guest.
And then the Guest Brahmana was extremely satisfied with that Brahman observing Unccha vow. Actually the guest Brahman was "Dharma" himself in the form of guest . And Dharma blessed the Brahma with gift of Swarga.
While offering the powered Satu to Dharma in the form of Brahman , few drops of that fell on the ground and this Blue eyed Mongoose ate that , and because that food ,earned by righteous manner , with purest intention to satisfy the hungry guest even in case of famine , and due to high Tapas of Brahmanas , the head and half body of Mongoose turned golden. He came to Ashwamedha Yajna of Yudhisthira with high hope that his half remaining body will also turn golden in this Yajna . but it wont. Mongoose is telling us the high fruits of
Brahmana who was firm in truth, and his penances, half of this my ample body has become golden. Ye regenerate ones, for converting the rest of my body into gold I repeatedly repair, with a cheerful heart, to the retreats of ascetics and the sacrifices performed by kings. Hearing of this sacrifice of the Kuru king endued with great wisdom, I came hither with high hopes. I have not, however, been made gold. Ye foremost of Brahmanas, it was for this that I uttered those words, viz., that this sacrifice can by no means compare with (the gift of) that prastha of powdered barley. With the grains of that prastha of powdered barley, I was made golden on that occasion. This great sacrifice however, is not equal to those grains. Even this is my opinion.' Having said those words unto all those foremost of Brahmanas, the mongoose disappeared from their sight. Those Brahmanas then returned to their respective homes.'
Here are the excerpts.
P. 156 "The Mongoose continued, 'Ye regenerate ones, I shall presently
tell you what the excellent fruit was of the gift, made by a Brahmana,
of a very little measure (of powdered barley) obtained by lawful
means. On that righteous spot of ground known by the name of
Kurukshetra, which is the abode of many righteous persons, there lived
a Brahmana in the observance of what is called the Unccha vow. That
mode of living is like unto that of the pigeon.
P. 157 On one
occasion, ye Brahmanas, there occurred a dreadful famine in the land.
During that time there was nothing stored in the abode of that
righteous Brahmana. The herbs and plants were all dried up and the
whole realm became void of foodstore. When the accustomed hours came
for eating, the Brahmana had nothing to eat. This occurred day after
day. All the members of his family were afflicted with hunger but were
obliged to pass the days as best they could. One day, in the month of
Jaishtha, while the Sun was in the meridian, the Brahmana was engaged
in picking up grains of corn. Afflicted by heat and hunger, he was
practising even this penance. Unable to obtain grains of corn, the
Brahmana soon became worn out with hunger and toil. Indeed, with all
the members of his family, he had no food to eat. That best of
Brahmanas passed the days in great suffering. One day, after the sixth
division came, he succeeded in obtaining a prastha of barley. That
barley was then reduced by those ascetics to powder for making what is
called Saktu of it. Having finished their silent recitations and other
daily rites, and having duly poured libations on the sacred fire,
those ascetics divided that little measure of powdered barley amongst
themselves so that the share of each came up to the measure of a
Kudava. 2 As they were about to sit down for eating, there came unto
their abode a guest. Beholding the person who came as a guest, all of
them became exceedingly glad. Indeed, seeing him, they saluted him and
made the usual enquiries of welfare.
p. 160 Having said so unto her,
the Brahmana took her share of the barley and gave it unto his guest.
At this the guest became gratified with the high-souled Brahmana
endued with great piety. With gratified soul, that first of regenerate
person, possessed of great eloquence, who was none else than the deity
of Righteousness in a human form, then addressed that foremost of
Brahmanas and said, 'O best of regenerate ones, I am exceedingly
gratified with this pure gift of thine, this gift of what was acquired
by lawful means by thee, and which thou didst freely part with,
agreeably to the rules of righteousness. Verily, this gift of thine is
being bruited about in Heaven by the denizens of that happy region.
Behold, flowers have been rained down from the firmament on the Earth.
After the deity of Righteousness had said these words, that Brahmana,
with his wife, son and daughter-in-law, proceeded to Heaven. After
that learned Brahmana, conversant with all duties, had thus ascended
to Heaven with his son, daughter-in-law, and wife numbering the
fourth, I came out of my hole. There with the scent of that powdered
barley, with the mire caused by the water (which the Brahmana had
given to his guest), with the contact (of my body) with the celestial
flowers that had been rained down, with the particles of the
barley-powder which that good man had given away, and the penances of
that Brahmana, my head became gold, Behold, in consequence of the gift
of that
P 162 . Brahmana who was firm in truth, and his penances, half
of this my ample body has become golden. Ye regenerate ones, for
converting the rest of my body into gold I repeatedly repair, with a
cheerful heart, to the retreats of ascetics and the sacrifices
performed by kings. Hearing of this sacrifice of the Kuru king endued
with great wisdom, I came hither with high hopes. I have not, however,
been made gold. Ye foremost of Brahmanas, it was for this that I
uttered those words, viz., that this sacrifice can by no means compare
with (the gift of) that prastha of powdered barley. With the grains of
that prastha of powdered barley, I was made gold on that occasion.
This great sacrifice however, is not equal to those grains. Even this
is my opinion.' Having said those words unto all those foremost of
Brahmanas, the mongoose disappeared from their sight. Those Brahmanas
then returned to their respective homes.'
In this story the Mongoose is telling us that not all great arrangements of rituals offer us the great merits , but a small offering with Nishkama karma ,observed with good Tapas and good and Dharmic miind are also capable of good merits like obtaining swarga and in some cases the great and grand sacrifices fail to deliver what simple offering of few grains of food with keeping high righteous in mind can bring about .
curse given to Dharma by Pitris
"Janamejaya said, 'Who was that mongoose with a golden head, that said all those words in a human voice? Asked by me, do thou tell me this.'
The Dharma which came there as guest as Brahmana was cursed By Pitris to become mongoose .
Once the Dharma wanted to test Rishi Jamadagni ,who was performing Shraddha of Pitris . The Dharma in the form of anger touched the milk kept away by rishi , by touching it and this polluting it. Rishi Jamadagni did not say anything to Dharma, but due to this deed of polluting their offerings ,Pitris cursed Dharma to become a mongoose .
"Vaisampayana said, 'Thou didst not ask me before and, therefore, I
did not tell thee. Hear as I tell thee who that mongoose was and why
he could assume a human voice. In former times, the Rishi Jamadagni
proposed to perform a Sraddha. His Homa cow came to him and the Rishi
milked her himself. He then placed the milk in a vessel that was new,
durable and pure. The deity Dharma, assuming the form of Anger,
entered that vessel of milk. Indeed, Dharma was desirous of
ascertaining what that foremost of Rishis.
would do when seeing some injury done to him. Having reflected thus,
Dharma spoiled that milk. Knowing that the spoiler of his milk was
Anger, the ascetic was not at all enraged with him. Anger, then,
assuming the form of a Brahmana lady, showed himself to the Rishi.
Indeed, Anger, finding that he had been conquered by that foremost one
of Bhrigu's race, addressed him, saying, 'O chief of Bhrigu's race, I
have been conquered by thee. There is a saying among men that the
Bhrigus are very wrathful. I now find that that saying is false, since
I have been subdued by thee. Thou art possessed of a mighty soul. Thou
art endued with forgiveness. I stand here today, owning thy sway. I
fear thy penances, O righteous one. Do thou, O puissant Rishi, show me
favour.'
"Jamadagni said, 'I have seen thee, O Anger, in thy embodied form. Go
thou whithersoever thou likest, without any anxiety. Thou hast not
done me any injury today. I have no grudge against thee. Those for
whom I had kept this milk are the highly blessed Pitris. Present
thyself before them and ascertain their intentions.' Thus addressed,
penetrated with fear, Anger vanished from the sight of the Rishi.
Through the curse of the Pitris he became a mongoose. He then began to gratify the Pitris in order to bring about an end of his
curse. By them he was told these words, 'By speaking disrespectfully
of Dharma thou shalt attain to the end of thy curse.' Thus addressed
by them he wandered over places where sacrifices were performed and
over other sacred places, employed in censuring great sacrifices. It
was he that came to the great sacrifice of king Yudhishthira.
Dispraising the son of Dharma by a reference to the prastha of
powdered barley, Anger became freed from his curse, for Yudhishthira
(as Dharma's son) was Dharma's self. Even this is what occurred in the
sacrifice of that high-souled king. Mongoose disappeared there in our
very sight.'
SECTION XCII