Ruru spares the dundubha snake after hearing its plea
Ruru has sworn to kill every snake he sees after one killed his wife. When he encounters a dundubha snake and raises his staff, the snake does not flee. It argues that it is a snake only by smell, not a biting snake, and that Ruru's indiscriminate vow shows he cannot tell right from wrong.
Ruru raised his staff, ready to strike. The snake before him was a dundubha, coiled on the forest path. For Ruru, this was not just any encounter. He had made a vow.
He spoke to the snake, explaining the reason for the violence he was about to commit. "My wife," he said, "whom I love as much as I love my own life, was bitten by a snake. O snake! At that time, I took a terrible vow that thereafter I would kill every snake that I saw. It is for that reason that I do violence to you and I shall deprive you of your life."
The dundubha did not try to slither away. It replied.
"O Brahmana! There are other snakes that bite mankind. The dundubhas are snakes only by smell; you should not kill them." It drew a distinction not of species, but of nature. It shared the form and the misfortune of being called a snake, but not the lethal intent. "We may share the same misfortune, but we do not share the same good fortune. We may share the same sorrows, but we do not share the same joys."
Then it aimed its argument at the vow itself. "Since you cannot differentiate between right and wrong, you should not kill the dundubhas."
The words landed. Ruru heard them, and he lowered his staff. He did not kill the dundubha. He was scared — and he thought the snake speaking with such clarity of dharma might be a rishi (sage) in another form.