"And you shall not afflict your neighbor; you shall fear God. I am Hashem, your God." Rashi explains: The Torah forbids us to afflict another person with words, as well as to give bad advice.
A few verses earlier, the Torah tells us: "When you sell something to your neighbor, do not deceive him." Deceiving another person in business is another kind of affliction.
One might ask: Which sin is more serious: afflicting one's neighbor with hurtful words, or deceiving him financially?
Rabbi Shimon bar Yochaitaught us: Insulting or harming another person with words is much more serious than deceiving or causing monetary harm.
The Sefer Hachinuch writes: "It is appropriate to be careful with words so as not to insult others, even indirectly. The Torah is very strict with this prohibition."
Most people are hurt more by words than by being cheated out of money. Likewise, we must be careful not to hurt children with words-except for educational purposes. This also applies to our own children or any other children in our home. Those who treat children docilely and do not cause them any distress will find blessings and Kavod (honor) in their lives.
To be clean from the prohibition of afflicting and making others feel bad, we must accustom ourselves to speaking with compassion to everyone.
The Midrash tells:
RebiHe served a meal for his students, which consisted of soft tongue and hard tongue. The students chose to eat the soft one.
Rebi said to them:
-My dear students: when you speak, you should also choose soft language.
RavYosef Dov Soloveitchick, the Rosh Yeshiva of Brisk, explained that all languages were fit to be swallowed. This is what the Midrash wanted to teach: not only are bad words forbidden, but even when there is a noticeable difference between two expressions, we should try to use the most appropriate one, anticipating the consequences that the word we are about to say may have.