The Jataka, Vol. II, tr. by W.H.D. Rouse, , at sacred-texts.com
"You are a fourfoot," etc.--This is a story told by the Master while at Jetavana, about a certain Elder well stricken in years.
Once, we are told, there happened to be a night service, and the Master had preached standing upon a slab of the jewelled staircase at the door of his scented cell. After delivering the discourse of the Blessed, he retired into his scented chamber; and the Captain of the Faith, saluting his Master, went back to his own cell again. Mahāmoggallāna too retired to his cell, and after a moment's rest returned to ask the Elder Sāriputta a question. As he asked and asked each question, the Captain of the Faith made it all clear, as though he were making the moon rise in the sky. There were present the four classes of disciples 2, who sat and heard it all. Then a thought came into the mind of one aged Elder. "Suppose," he thought, "I can puzzle Sāriputta before all this crowd, by asking him some question? They will all think, What a clever fellow! and I shall gain great credit and repute." So he rose up in the crowd, and stepping near to the Elder, stood on one side, and said, "Friend Sāriputta, I too have a question for you; will you let me speak? Give me a decision in discrimination or in undiscrimination, in refutation or in acceptation, in distinction or in counter-distinction 3." The Elder looked at him. "This old man," thought he, "stands within the sphere of desire still; he is empty, and knows nothing." He said not a single word to him for very shame; laying his fan down, he rose from his seat,  and returned to his cell. And Elder Moggallāna likewise returned to his cell. The bystanders jumped up, crying, "Seize this wicked old fellow, who wouldn't let us hear the sweet words of the sermon!" and they mobbed him. Off he ran, and fell through a hole in the corner of a cesspool just outside the monastery; when he got up he was all over filth. When the people saw him, they felt sorry for it, and want away to the Master. He asked, "Why have you come at this unseasonable hour, laymen?" They told him what had happened. "Laymen," said he, "this is not the only time this old man has been pulled up, and not knowing his own power, pitted himself against the strong, only to be covered all over with filth. Long, long ago he knew not his powers, pitted himself against the strong, and was covered with filth as he is covered now." Then, at their request, he told them a story of the olden time.
Once upon a time, when Brahmadatta was king of Benares, the Bodhisatta was a Lion who dwelt in a mountain cave in the Himalayas. Hard by were a multitude of Boars, living by a lakeside; and beside the same lake lived a company of anchorites in huts made of leaves and the branches of trees.
One day it so happened that the Lion had brought down a buffalo or elephant or some such game; and, after eating what he listed, he went down to drink at this lake. Just as he came out, a sturdy Boar happened to be feeding by the side of the water. "He'll make a meal for me some other day," thought the Lion. But fearing that if the Boar saw him, he might never come there again, the Lion as he came up out of the water slunk away to the side. This the Boar saw; and at once the thought came into his mind,--"This is because he has seen me, and is afraid! He dare not come nigh me, and off he runs for fear! This day shall see a fight between me and a lion!" So he raised his head, and made challenge against the Lion in the first stanza:
 The Lion gave ear. "Friend Boar," he said, "to-day there will be no fight between you and me. But this day week let us fight it out in this very spot." And with these words, he departed.
The Boar was highly delighted in thinking how he was to fight a lion; and he told all his kith and kin about it. But the tale only terrified them. "You will be the bane of us all," they said, "and yourself to boot. You know not what you can do, or you would not be so eager to do battle with a lion. When the Lion comes, he'll be the death of you and all of us as well; do not be so violent! "These words made the Boar fear on his part. "What am I to do, then?" he asked. Then the other roars advised him to roll about in the anchorites' dunghill for the next seven days, and let the muck dry on his body; then on the seventh day he should moisten himself with dewdrops, and be first at the trysting place; the must find how the wind should lie, and get to the windward; and the Lion, being a cleanly creature, would spare his life when he had a whiff of him.
So accordingly he did; and on the day appointed, there he was. No sooner had the Lion scented him, and smelt the filth, says he, "Friend Boar, a pretty trick this! Were you not all besmeared with filth, I should have had your life this very day. But as it is, bite you I cannot, nor so much as touch you with my foot. Therefore I spare your life." And then he repeated the second stanza:--
Then the Lion turned away, and procured his day's food; and anon, after a drink at the lake, he went back again to his cave on the mountain. And the Boar told his kindred how he had beaten the Lion!  But they were terrified for fear the Lion should come again another day and be the death of them all. So they ran away and betook them to some other place.
When the Master had ended this discourse, he identified the Birth: "The Boar of those days is now the ancient Elder, and I myself was the Lion."
7:1 Fausbøll, Ten Jātakas, pp. 12, 63, 94 (he compares Nos. 278 and 484); R. Morris in Contemp. Rev. 1881, vol. 39, p. 737.
7:2 Monks, nuns, laymen and lay sisters.
7:3 These words appear to be nonsense.