The answer is: Oaths

Matt 5:36

In the Sermon on the Mount, Jesus uses the expression about hair color to underscore a powerful point about truthfulness and the futility of making oaths. When He refers to "making one hair on your head black or white," He's highlighting our limited control over nature and, by extension, our own lives. It’s a reminder that we should not rely on the swearing of oaths as a way to assure our honesty. Instead, Jesus advocates for straightforwardness—just let your "yes" be "yes" and your "no" be "no."

Now, isn't it fascinating that during Jesus’ time, oaths held significant power in society? People would swear by everything—the Temple, the altar, even their own heads—to prove their truthfulness. Yet, despite all that seriousness, the Bible encourages a different, better level of integrity founded solely on one’s word. This idea resonates with the wisdom of Proverbs, such as “a man is as good as his word.”

On a lighter note, think of how today we say someone's word is their bond. That idiom is a direct reflection of that Gospel spirit—emphasizing reliability and uprightness without the need for verbose oaths. Moreover, Jesus' urban context in Galilee, where people engaged with diverse cultures and practices, reflects a timely relevance to our own quite complicated, interconnected world today. So the next time you hear someone pledge their honesty, it’s worth pondering whether words and actions are truly in sync!