The Bodhisatta was once a snake bite doctor, and, on one occasion, when a countryman had been bitten by a snake, the doctor ordered the snake to be brought and asked it to suck the poison out of the wound. This the snake refused to do even though threatened with death by the doctor.
The story was told in reference to a vow taken by Sáriputta. Some villagers once brought some meal cakes to the monastery, and when the monks present there had eaten, it was suggested that what remained should be saved for those monks who were absent in the village. This was done, but a young colleague of Sáriputta, arriving very late, found that Sáriputta had already eaten his portion, whereat he was very disappointed. Sáriputta immediately vowed never again to touch meal cakes, and the Buddha said that Sáriputta would never return to anything which he had once renounced. The snake is identified with Sáriputta. J.i.310f.