This tale may not be new but for me it is and has a taught:
On a path that went by a village in Bengal there lived a cobra who used to bite people on their way to worship at the temple there. As the incidents increased, everyone became fearful, and many refused to go to the temple. The Swami who was the master at the temple was aware of the problem and took it upon himself to put an end to it. Taking himself to where the snake dwelt, he used a mantra to call the snake to him and bring it into submission.
The Swami then said to the snake that it was wrong to bite the people who walked along the path to worship and made him promise sincerely that he would never do it again. Soon it happened that the snake was seen by a passer-by upon the path, and it made no move to bite. Then it became known that the snake had somehow been made passive, and people grew unafraid. It was not long before the village boys were dragging the poor snake along behind them as they ran laughing here and there. When the temple Swami passed that way again he called the snake to see if he had kept his promise–
The snake humbly and miserably approached the Swami, who exclaimed, ‘You are bleeding! Tell me how this has come to be.’ The snake was near tears and blurted out that he had been abused ever since he made his promise to the Swami. ‘I told you not to bite,’ said the Swami, ‘but I did not tell you not to hiss!