The Jataka, Vol. II, tr. by W.H.D. Rouse, , at sacred-texts.com
"Creature, your egg-born enemy," etc.--This story the Master told during a sojourn at Jetavana, about two officers who had a quarrel. The circumstances have been given above in the Uraga Birth 1. Here, as before, the Master said, "This is not the first time, Brethren, these two nobles have been reconciled by me; in former times I reconciled them too." Then he told an old story.
Once on a time, when Brahmadatta was king of Benares, the Bodhisatta was born in a certain village as one of a brahmin family. When he came of age,  he was educated at Takkasilā; then, renouncing the world he became a recluse, cultivated the Faculties and the Attainments, and dwelt in the region of Himalaya, living upon wild roots and fruits which he picked up in his goings to and fro.
At the end of his cloistered walk lived a Mongoose in an ant-heap; and not far off, a Snake lived in a hollow tree. These two, Snake and Mongoose, were perpetually quarrelling. The Bodhisatta preached to them the misery of quarrels and the blessing of peace, and reconciled the two together, saying, "You ought to cease your quarrelling and live together at one."
When the Serpent was abroad, the Mongoose at the end of the walk lay with his head out of the hole in his ant-hill, and his mouth open, and
thus fell asleep, heavily drawing his breath in and out. The Bodhisatta saw him sleeping there, and asking him, "Why, what are you afraid of?" repeated the first stanza:
"Father," said the Mongoose, "never despise a former enemy, but always suspect him ": and he repeated the second stanza:
 "Fear not," replied the Bodhisatta. "I have persuaded the Snake to do you no harm; distrust him no more." With this advice, he proceeded to cultivate the Four Excellences, and set his face toward Brahma's heaven. And the others too passed away to fare hereafter according to their deeds.
Then this lesson ended, the Master identified the Birth: "The two noblemen were at that time Snake and Mongoose, and I was myself the ascetic."
36:1 Above, No. 154.
37:1 Lit. 'O viviparous one.'