在古代文学作品中，《公冶长背诺》是一则引人深思的故事。这个故事不仅富有哲理，而且对后世产生了深远的影响。以下为原文及其现代汉语翻译：

原文：

公冶长者，鲁人也。尝游于齐，遇一老翁，谓曰：“吾有疾，将死矣。吾有一子，年方十岁，汝可教之。”公冶长许诺而去。后数月，公冶长复至齐，见老翁之子已能诵读诗书，技艺超群，甚感欣慰。

然一日，公冶长偶闻老翁之子私窃邻家财物，心甚忧之。遂告之于老翁，言其子之过失。老翁听罢，叹曰：“吾儿虽有过，然汝背吾之托，实乃不义之举。”

公冶长闻言，深感愧疚，自责不已。

翻译：

There was a man named Gongye Chang who lived in the state of Lu. Once, he traveled to the state of Qi and met an old man. The old man said to him, "I am very sick and will soon die. I have a son who is only ten years old; you must teach him." Gongye Chang promised and left. After several months, when Gongye Chang returned to Qi, he found that the old man's son could already read poetry and books, and his skills were extraordinary, which made Gongye Chang feel very satisfied.

However, one day, Gongye Chang accidentally heard that the old man's son had stolen something from a neighbor's house, and he felt very worried about it. He then told this to the old man, mentioning the son's misconduct. Upon hearing this, the old man sighed and said, "Although my son has made mistakes, your breach of promise is indeed an unjust act."

After hearing these words, Gongye Chang felt extremely ashamed and blamed himself deeply.

这则故事告诉我们，承诺一旦做出，就应当尽力履行，不可轻易违背，否则会伤害他人，也会让自己陷入道德困境。同时，它也提醒我们，面对他人的错误时，应该采取适当的方式去解决，而不是简单地揭发或指责。