God worded this commandment differently from what we might expect. He might have said, "Thou shalt not lie."The wording indicates the emphasis, which was specifically bearing false witness, namely, character assassination, another form of killing and stealing. The word "witness"(Heb. ed) refers to testimony given in legal cases. "Neighbor"(Heb. rea') focuses on a fellow member of the covenant community but is broad enough to include all other human beings (cf. Exod. 11:2; Lev. 19:18, 34). Integrity, honesty, and faithfulness in speech are in view, especially situations in which testimony determines a person's fate. The more general prohibition against lying appears elsewhere (Lev. 19:11-12). The ninth commandment deals with our speech as does the third (cf. James 3).
This command covers all kinds of slander (cf. Ps. 101:5). Perjury in court is in view primarily. Nevertheless whenever we distort the truth when we speak we have the potential of ruining a life (cf. the fates of Naboth and Jesus Christ). Satan is the source and father of lies (John 8:44; cf. Acts 5:3). The Fall resulted from a lie (Gen. 3:4). God hates lying (Prov. 6:16-19) and is the infallible lie detector. Flattery can be a form of lying. A question can slander (Job 1:8-9) as can silence if by keeping silent we give tacit approval to a lie. However we do not always need to tell all we know. Withholding information does not always constitute lying.
Lying, and bearing false witness in particular, should never characterize the Christian (Col. 3:9-17).
(NT only) to listen to the NET Bible 
