The Jataka, Volume I, tr. by Robert Chalmers, , at sacred-texts.com
"What? Leave untasted."--This story was told by the Master while at Jetavana, about some drugged liquor.
Once on a time the tipplers of Sāvatthi met to take counsel, saying, "We've not got the price of a drink left; how are we to get it?"
"Cheer up!" said one ruffian; "I've a little plan."
"What may that be?" cried the others.
"It's Anātha-piṇḍika's custom," said the fellow, "to wear his rings and richest attire, when going to wait upon the king. Let us doctor some liquor with a stupefying drug and fit up a drinking-booth, in which we will all be sitting when Anātha-piṇḍika passes by. 'Come and join us, Lord High Treasurer,' we'll cry, and ply him with our liquor till he loses his senses. Then let us relieve him of his rings and clothes, and get the price of a drink."
His plan mightily pleased the other rogues, and was duly carried out. As Anātha-piṇḍika was returning, they went out to meet him and invited him  to come along with them; for they had got some rare liquor, and he must taste it before he went.
"What'?" thought he, "shall a believer, who has found Salvation, touch strong drink? Howbeit, though I have no craving for it, yet will I expose these rogues." So into their booth he went, where their proceedings soon shewed him that their liquor was drugged; and he resolved to make the rascals take to their heels. So he roundly charged them with doctoring their liquor with a view to drugging strangers first and robbing then afterwards. "You sit in the booth you have opened, and you praise up the liquor," said he; "but as for drinking it, not one of you ventures on that. If it is really undrugged, drink away at it yourselves." This summary exposure made the gang take to their heels, and Anātha-piṇḍika went off home. Thinking he might as well tell the incident to the Buddha, he went to Jetavana and related the story.
"This time, layman," said the Master, "it is you whom these rogues have tried to trick; so too in the past they tried to trick the good and wise of those days." So saying, at his hearer's request, he told this story of the past.
Once on a time when Brahmadatta was reigning in Benares, the Bodhisatta was Treasurer of that city. And then too did the same gang of tipplers, conspiring together in like manner, drug liquor, and go forth to meet him in just the same way, and made just the same overtures. The Treasurer did not want to drink at all, but nevertheless went with them, solely to expose them. Marking their proceedings and detecting their scheme, he was anxious to scare them away and so represented that it would be a gross thing for him to drink spirits just before going to the king's palace. "Sit you here," said he, "till I've seen the king and am on my way hack; then I'll think about it."
On his return, the rascals called to him, but the Treasurer, fixing his eye on the drugged bowls, confounded them by saying, "I like not your
ways. Here stand the bowls as full now as when I left you; loudly as you vaunt the praises of the liquor, yet not a drop passes your own lips. Why, if it had been good liquor, you'd have taken your own share as well. This liquor is drugged!" And he repeated this stanza:--
After a life of good deeds, the Bodhisatta passed away to fare according to his deserts.
His lesson ended, the Master identified the Birth by saying, "The rascals of to-day were also the rascals of those bygone days; and I myself was then Treasurer of Benares."