Exodus 20:16 “You shall not bear false witness against your neighbor.”
This Ninth Commandment covers a false testimony when given in a Hebrew court of justice— “and this offence has generally been made punishable by law. It was peculiar to the Hebrew legislation that it not only forbade and punished (Deuteronomy 19:16-20) false testimony of this extreme kind...“ (Ellicott's Commentary for English Readers)
“If a malicious witness rises up against a man to accuse him of wrongdoing, then both the men who have the dispute shall stand before the LORD, before the priests and the judges who will be in office in those days. The judges shall investigate thoroughly, and if the witness is a false witness and he has accused his brother falsely, then you shall do to him just as he had intended to do to his brother. Thus you shall purge the evil from among you. The rest will hear and be afraid, and will never again do such an evil thing among you. Thus you shall not show pity: life for life, eye for eye, tooth for tooth, hand for hand, foot for foot.” (Deuteronomy 19:16-21)
“So they hanged Haman on the gallows that he had prepared for Mordecai.” (Esther 7:10) But this Commandment also "denounced also the far commoner, yet scarcely less injurious, practice of spreading untrue reports about others, thus injuring them in men’s esteem." (Ellicott's Commentary for English Readers)) Anything false which “tends to injure another in his goods, person, or character, is against the spirit and letter of this law.” (Adam Clarke)
“Who steals my purse, steals trash,
But he who filches from me my good name,
Robs me of that which not enriches him,
Yet leaves me poor indeed.” (William Shakespeare)
It is dull to make real research into the facts, as used to be the practice.
1) Social- “‘Come, let us enjoy ourselves, and abuse our neighbours,’ is the real meaning of many an invitation to social intercourse... A man that beareth false witness against his neighbour is a maul, and a sword, and a sharp arrow. If all the words of ill-natured calumny, of uncharitable construction of their friends which people speak, could be made inaudible, what stretches of silence would open out in much animated talk!” (A. MacLaren)
2) Political- “False witness can reach to nations, organisations, political movements as well as individuals. The habit of putting the worst construction upon the intentions of foreign powers is what feeds the mutual jealousies that ultimately blaze out in war. The habit of thinking of rival politicians as deliberately false and treasonable is what lowers the standard of the noblest of secular pursuits, until each party, not to be undone, protests too much, raises its voice to a falsetto to scream its rival down, and relaxes its standard of righteousness lest it should be outdone by the unscrupulousness of its rival.” (Expositor's Bible) “If some fairy could treat our newspapers as the Russian censors do, and erase all the lies about the opposite side, which they report and coin, how many blank columns there would be!” (A. MacLaren)
3) Religious- False testimonies even reaches to the fabric of the church- when you condemn a man or woman and spread innuendos against them for biblical doctrine that you yourself have not personally and prayerfully investigated, searching the Old and New Testament for those “two or three witnesses” (Deuteronomy 19:15) to purify your creed, seeing if these things are of God.
Check yourself with the "spiritual snopes of truth" in all arenas. “You shall not bear false witness” etc.- “Neither bear it, nor hear it; raise, nor receive wrong reports of another; [Deut. 19:16] make a lie, nor love it when it is made. [Rev. 22:15] The truth must be spoken, and that in love [with the spiritual goal of salvation of a wayward soul]. Doeg had a false tongue, though he spoke nothing but truth against David. [Psa. 120:3]” (John Trapp)—yet he acted with a motive to fuel Saul’s suspicions and passions by erroneous conclusions, stealing David’s praise for himself.