The Jataka, Vol. II, tr. by W.H.D. Rouse, , at sacred-texts.com
"Lion's claws and lion's paws," etc.--This is a story told by the Master whilst at Jetavana, about Kokālika. They say that Kokālika one day hearing a number of wise Brethren preaching, desired to preach himself; all the rest is like the circumstances given in a previous tale 1. This time again the Master on hearing of it said, "Not this once only has Kokālika been shown up for what he was worth by means of his own voice; the very same thing happened before." And he told a story.
Once on a time, when Brahmadatta was king of Benares, the Bodhisatta was a Lion in the Himalaya mountains, and he had a cub by a she jackal who mated with him. The cub was just like his sire in toes, claws, mane, colour, figure--all these; but in voice he was like his dam.
One day, after a shower of rain, all the Lions were gambolling together and roaring; the cub thought he would like to roar too, and yelped like a jackal. On hearing which all the Lions fell silent at once! Another cub of the same sire, own brother of this one, heard the sound, and said, "Father, yon lion is like us in colour and everything except in voice. Who's he?" in asking which question he repeated the first stanza:
 In answer the Bodhisatta said, "It's your brother, the Jackal's cub; like me in form, but in voice like his dam." Then he gave a word of advice to the other cub--"My dear son, as long as you live here keep a quiet tongue in your head. If you give tongue again, they'll all find out that you are a Jackal." To drive the advice home he repeated the second stanza:--
After this advice the creature never again so much as tried to roar.
When the Master had finished this discourse, he identified the Birth:--"In those days Kokālika was the Jackal, Rahula was the brother cub, and the king of beasts was I myself."
75:1 No. 172; compare no. 189. Kokālika is often alluded to in this way; cp. nos. 117, 481. There is a story in the Cullavagga i. 18. 3, turning on a similar point; a hen has a chick by a crow, and when it would city cock-a-doodle-doo it caws, and vice versa (Vinaya Texts, S. B. E., ii. p. 362).