Once on a time, when Brahmadatta was reigning in Benares, the Bodhisatta was born into a family of doctors skilled in the cure of snake bites, and when he grew up, he practiced for a livelihood.
Now it fell out that a countryman was bitten by a snake; and without delay his relatives quickly fetched the doctor. Said the Bodhisatta, “Shall I extract the venom with the usual antidotes, or have the snake caught and make it suck its own poison out of the wound?” “Have the snake caught and make it suck the poison out.” So he had the snake caught, and asked the creature, saying “Did you bite this man?” “Yes, I did,” was the answer. “Well then, suck your own poison out of the wound again.” “What? Take back the poison I have once shed!” cried the snake; “I never did, and I never will.” Then the doctor made a fire with wood, and said to the snake, “Either you suck the poison out, or into the fire you go.”
“Even though the flames be my doom, I will not take back the poison I have once shed,” said the snake, and repeated the following stanza:-
May shame be on the poison which, once shed,
To save my life, I swallow down again!
More welcome death then life by weakness bought!
With these words, the snake moved towards the fire! But the doctor barred its way, and drew out the poison with simples and charms, so that the man was whole again. Then he unfolded the Commandments to the snake, and set it free, saying, “Henceforth do harm to none.