The Jataka, Volume I, tr. by Robert Chalmers, , at sacred-texts.com
"Where saintliness."--This story was told by the Master while at Jetavana, about a hypocrite. When the Brother's hypocrisy was reported to him, the Master said, "This is not the first time he has shewn himself a hypocrite; he was just the sane in times gone by." So saying he told this story of the past.
Once on a time when Brahmadatta was reigning in Benares, the Bodhisatta was born rat, perfect in wisdom, and as big as a young boar.
He had his dwelling in the forest and many hundreds of other rats owned his sway.
Now there was a roving jackal who espied this troop of rats and fell to scheming how to beguile and eat them. And he took up his stand near their home with his face to the sun, snuffing up the wind, and standing on one leg. Seeing this when out on his road in quest of food, the Bodhisatta conceived the jackal to be a saintly being, and went up and asked his name.
"'Godly' is my name," said the jackal. "Why do you stand only on one leg?" "Because if I stood on all four at once, the earth could not bear my weight. That is why I stand on one leg only." "And why do you keep your mouth open?" "To take the air. I live on air; it is my only food." "And why do you face the sun?" "To worship him." "What uprightness!" thought the Bodhisatta, and thenceforward he made a point of going, attended by the other rats, to pay his respects morning and evening to the saintly jackal. And when the rats were leaving, the jackal seized and devoured the hindermost one of them, wiped his lips, and looked as though nothing had happened. In consequence of this the rats grew fewer and fewer, till they noticed the gaps in their ranks, and wondering why this was so, asked the Bodhisatta the reason. He could not make it out, but suspecting the jackal,  resolved to put him to the test. So next day he let the other rats go out first and himself brought up the rear. The jackal made a spring on the Bodhisatta who, seeing him coming, faced round and cried, "So this is your saintliness, you hypocrite and rascal!" And he repeated the following stanza:--
So saying, the king of the rats sprang at the jackal's throat and bit his windpipe asunder just under the jaw, so that he died. Back trooped the other rats and gobbled up the body of the jackal with a 'crunch, crunch, crunch';--that is to say, the foremost of them did, for they say there was none left for the last-corners. And ever after the rats lived happily in peace and quiet.
His lesson ended, the Master made the connection by saying, "This hypocritical Brother was the jackal of those days, and I the king of the rats."
282:1 Though the foregoing prose relates to a jackal, the stanza speaks of a cat, as does the Mahābhārata in its version of this story.