The Jataka, Vol. III, tr. by H.T. Francis and R.A. Neil, , at sacred-texts.com
"Seven red fish," etc.—This story was told by the Master while living at Jetavana, about a gift of all the Buddhist requisites. A certain landowner at Sāvatthi, they say, provided all the requisites for the Brotherhood with Buddha at its head, and setting up a pavilion at his house door, he invited all the
company of priests with their chief Buddha, seated them on elegant seats prepared for them, and offered them a variety of choice and dainty food. And saying, "Come again to-morrow," he entertained them for a whole week, and on the seventh day he presented Buddha and the five hundred priests under him with all the requisites. At the end of the feast the Master, in returning thanks, said, "Lay Brother, you are right in giving pleasure and satisfaction by this charity. For this is a tradition of wise men of old, who sacrificed their lives for any beggars they met with, and gave them even their own flesh to eat." And at the request of his host he related this old-world legend.
Once upon a time when Brahmadatta was reigning in Benares, the Bodhisatta came to life as a young hare and lived in a wood. On one side of this wood was the foot of a mountain, on another side a river, and on the third side a border-village. The hare had three friends—a monkey, a jackal and an otter. These four wise creatures lived together  and each of them got his food on his own hunting-ground, and in the evening they again came together. The hare in his wisdom by way of admonition preached the Truth to his three companions, teaching that alms are to be given, the moral law to be observed, and holy days to be kept. They accepted his admonition and went each to his own part of the jungle and dwelt there.
And so in the course of time the Bodhisatta one day observing the sky, and looking at the moon knew that the next day would be a fast-day, and addressing his three companions he said, "To-morrow is a fast-day. Let all three of you take upon you the moral precepts, and observe the holy day. To one that stands fast in moral practice, almsgiving brings a great reward. Therefore feed any beggars that come to you by giving them food from your own table." They readily assented, and abode each in his own place of dwelling.
On the morrow quite early in the morning, the otter sallied forth to seek his prey and went down to the bank of the Ganges. Now it came to pass that a fisherman had landed seven red fish, and stringing them together on a withe, he had taken and buried them in the sand on the river's bank. And then he dropped down the stream, catching more fish. The otter scenting the buried fish, dug up the sand till he came upon them, and pulling them out cried aloud thrice, "Does any one own these fish?" And not seeing any owner he took hold of the withe with his teeth and laid the fish in the jungle where he dwelt, intending to eat them at a fitting time. And then he lay down, thinking how virtuous he was! The jackal too sallied forth in quest of food and found in the hut of a field-watcher two spits, a lizard and a pot of milk-curd. And after thrice crying aloud, "To whom do these belong?" and not finding an owner, he put on his neck the rope for lifting the pot, and grasping the spits and the
lizard with his teeth, he brought and laid them in his own lair, thinking, "In due season I will devour them," and so lay down,  reflecting how virtuous he had been.
The monkey also entered the clump of trees, and gathering a bunch of mangoes laid them up in his part of the jungle, meaning to eat them in due season, and then lay down, thinking how virtuous he was. But the Bodhisatta in due time came out, intending to browse on the kuça grass, and as he lay in the jungle, the thought occurred to him, "It is impossible for me to offer grass to any beggars that may chance to appear, and I have no oil or rice and such like. If any beggar shall appeal to me, I shall have to give him my own flesh to eat." At this splendid display of virtue, Sakka's white marble throne manifested signs of heat. Sakka on reflection discovered the cause and resolved to put this royal hare to the test. First of all he went and stood by the otter's dwelling-place, disguised as a brahmin, and being asked why he stood there, he replied, "Wise Sir, if I could get something to eat, after keeping the fast, I would perform all my priestly duties." The otter replied, "Very well, I will give you some food," and as he conversed with him he repeated the first stanza:—
O brahmin, eat thy fill, I pray, and stay within this wood.
The brahmin said, "Let be till to-morrow. I will see to it by and bye." Next he went to the jackal, and when asked by him why he stood there, he made the same answer. The jackal, too, readily promised him some food, and in talking with him repeated the second stanza:—
Two spits to roast the flesh withal I wrongfully did steal:
Such as I have I give to thee: O brahmin, eat, I pray,
If thou shouldst deign within this wood a while with us to stay.
Said the brahmin, "Let be till to-morrow. I will see to it by and bye." Then he went to the monkey, and when asked what he meant by standing there, he answered just as before. The monkey readily offered him some food, and in conversing with him gave utterance to the third stanza:—
’Tis thine to enjoy, if thou canst dwell content in forest glade.
Said the brahmin, "Let be till to-morrow. I will see to it by and bye." And he went to the wise bare, and on being asked by him why he stood there, he made the same reply. The Bodhisatta on hearing what he wanted was highly delighted, and said, "Brahmin, you have done well in coming to me for food. This day will I grant you a boon that I have never granted before, but you shall not break the moral law by taking
animal life. Go, friend, and when you have piled together logs of wood, and kindled a fire, come and let me know,  and I will sacrifice myself by falling into the midst of the flames, and when my body is roasted, you shall eat my flesh and fulfil all your priestly duties." And in thus addressing him the hare uttered the fourth stanza:—
But roast with fire my flesh I yield, if thou with us wouldst live.
Sakka, on hearing what he said, by his miraculous power caused a heap of burning coals to appear, and came and told the Bodhisatta. Rising from his bed of kuça grass and coming to the place, he thrice shook himself that if there were any insects within his coat, they might escape death. Then offering his whole body as a free gift he sprang up, and like a royal swan, alighting on a cluster of lotuses, in an ecstasy of joy he fell on the heap of live coals. But the flame failed even to heat the pores of the hair on the body of the Bodhisatta, and it was as if he had entered a region of frost. Then he addressed Sakka in these words: "Brahmin, the fire you have kindled is icy-cold: it fails to beat even the pores of the hair on my body. What is the meaning of this?" "Wise sir," he replied, "I am no brahmin. I am Sakka, and I have come to put your virtue to the test." The Bodhisatta said, "If not only thou, Sakka, but all the inhabitants of the world were to try me in this matter of almsgiving, they would not find in me any unwillingness to give," and with this the Bodhisatta uttered a cry of exultation like a lion roaring. Then said Sakka to the Bodhisatta, "O wise hare, he thy virtue known throughout a whole won." And squeezing the mountain, with the essence thus extracted, he daubed the sign of a hare on the orb of the moon. And after depositing the hare on a bed of young kuça grass, in the same wooded part of the jungle, Sakka returned to his own place in heaven.  And these four wise creatures dwelt happily and harmoniously together, fulfilling the moral law and observing holy days, till they departed to fare according to their deeds.
The Master, when he had ended his lesson, revealed the Truths and identified the Birth:—At the conclusion of the Truths the householder, who gave as a free-gift all the Buddhist requisites, attained fruition of the First Path:—" At that time Ānanda was the otter, Moggallāna was the jackal, Sāriputta the monkey, and I myself was the wise hare."
34:1 See R. Morris, Folk-Lore Journal, ii. 336 and 370. Jātakamālā, No. 6. On the wide-spread prevalence of the legend of the Hare in the Moon, see T. Harley's Moon-Lore, p. 60.