From TorahVort.com
Speech
Wronging a Person through Speech
In Parshah Behar (Leviticus 25:17) it states in a verse, "You shall not wrong one another." This has traditionally been interpreted as wronging a person through speech. It includes any statement that may embarrass, insult or deceive a person, or resulting in a person suffering emotional pain or distress.
Here are some commonly-used examples of behavior that is forbidden by this commandment:
One is not allowed to call a person by a derogatory nickname, or by any other embarrassing name, even if he is used to it.
One is not allowed to ask an uneducated person for an opinion on a scholarly matter (that would potentially draw attention to his lack of knowledge or education).
One is not allowed to ask a merchant how much he would sell something for if you one has no intention of buying.
One is not allowed to refer someone to another person for assistance when you know the other person cannot help (in other words, it's a violation of Jewish law to give someone the run-around!).
One is not allowed to deceive a person, even if no harm is done by the deception
One is not allowed to sell a person damaged goods without identifying the damage, even if the price you give is fair for the goods in their damaged condition.
One is not allowed to offer a person a gift or invite a person to dinner if they know that the person will not accept.
One is not allowed to compliment a person if the person does not mean it.
