从前，有一位东郭先生，他心地善良，乐于助人。一天，他在路上遇到一只受伤的狼，狼哀求东郭先生救它一命。东郭先生出于怜悯之心，把狼藏在自己的书袋里。

不久后，猎人追了上来，询问东郭先生是否见过一只狼。东郭先生为了保护狼，谎称没有见过。猎人离开后，狼从书袋中跳出来，露出凶狠的本性，准备吃掉东郭先生。就在千钧一发之际，一位农夫路过，听到了他们的争执，便劝说狼不要忘恩负义，并且教训了狼一顿。

这个故事告诉我们，对于那些忘恩负义的人或动物，我们不能一味地宽容和纵容，而应该保持警惕，以免受到伤害。

以下为英文翻译：

Once upon a time, there was an old man named Mr. Dongguo who was kind-hearted and always willing to help others. One day, on his way home, he met a wounded wolf begging for help. Moved by compassion, Mr. Dongguo hid the wolf in his book bag.

Soon after, a hunter came along and asked whether Mr. Dongguo had seen a wolf. In order to protect the wolf, Mr. Dongguo lied that he hadn't seen it. After the hunter left, the wolf jumped out of the bag and showed its ferocious nature, intending to eat Mr. Dongguo. Just as things were about to get serious, a farmer happened to pass by and heard their argument. The farmer then advised the wolf not to be ungrateful and taught the wolf a lesson.

This story tells us that we should not be too tolerant or indulgent towards those who are ungrateful, but instead remain vigilant to avoid being hurt.

通过这个故事，我们可以学到，在面对忘恩负义之人时，我们需要更加谨慎，而不是一味地给予宽容。同时，这也提醒我们在生活中要明辨是非，善恶分明，做一个有原则的人。