Translation by Yehoshua Siskin
Words that we say do not leave a physical mark, but they do not disappear. At the moment that we say something, we create a new reality in the world. This is the subject that opens this week's Torah portion: Moshe gathers the heads of the tribes tells them that if someone promises something, he should not violate his promise: "He shall not violate his word; according to whatever came out of his mouth, he shall do." (Numbers 30:3) Rashi explains: "He shall not violate his word: He shall not profane his word, he shall not make his word unholy." That is to say: the words that come out of our mouth are meant to be holy, and it is forbidden to utter unholy words.
Speech expresses what is in the soul, and every year, as Tisha B'Av approaches, we read this parasha that reminds us to create a different kind of spoken culture. "Life and death are in the power of the tongue." (Proverbs 18:21) Words can destroy the world but also give it life. This is a reminder that all of us possess the most powerful weapon without having to carry a license: the ability to speak.
It's very easy to criticize others in this area, especially public figures, but we are also susceptible to verbal indiscretions. According to Sefat Emet: "This is the purpose of life - to improve and refine our speech."