All Biblical quotations are from the ESV (English Standard Version), unless noted otherwise.
Where it is found, and what it says.
The ninth commandment is found in Exodus 20:16, and in Deuteronomy 5:20. Here is what it says: "You shall not bear false witness against your neighbor."
What exactly does this command prohibit?
We know what the word "false" means, but it will help us to know what the word "witness" means. The Hebrew dictionary in The Strongest Strong's Concordance says the word for "witness" means "witness, testimony; an object that serves as a memorial or a person giving of legal evidence." So, then, this command prohibits giving false evidence against our neighbor. However, we know that the prohibition applies to anyone else, even our enemies, for we are always to be truthful.
Jesus Christ told us the answer in Matthew 15:19, in which he said: "For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander." So the source of this sin, as with all sins, is a corrupt heart. Even if we are not guilty of bearing false witness, all the sins we have committed and will yet commit come from a corrupt heart.
According to Revelation 21:8, it is very serious. It says:"But as for the cowardly, the faithless, the detestable, as for murderers, the sexually immoral, sorcerers, idolaters, and all liars, their portion will be in the lake that burns with fire and sulfur, which is the second death." To bear false witness is to lie. And Revelation 21:8 tells us what the result will be for those who face God as unforgiven liars. But any sin will be forgiven by Jesus Christ, if the guilty person admits to him their guilt and believes on him as Savior. If you are in need of salvation, the Bible says: "Believe in the Lord Jesus Christ and you will be saved." (New King James Version)
The wisdom of this command.
It is easy to see the wisdom of this command. It puts the brakes on our sinful natures which would lead us to be false witnesses for a variety of reasons. If a family member has abused us sexually or physically or emotionally or verbally, our sinful natures would prompt us to retaliate, which might be done by bearing false witness against them by knowingly stating they had done more harm to us than they, in fact, did. We might do the same if we have been mistreated by a neighbor or a boss or a fellow-employee.
However, it is never right to bear false witness against someone. We must resist the urge to do so. We can go to the Lord in prayer and tell him that we are struggling with the urge to retaliate by being a false witness, and he will help us. We can claim the truth of 1 Corinthians 10:13, which says: "No temptation has overtaken you that is not common to man. God is faithful, and he will not let you be tempted beyond your ability, but with the temptation he will also provide a way of escape, that you may be able to endure it."
What should we do, if we have borne false witness against someone?
First, we must admit it to God. Proverbs 28:13 says: "Whoever conceals his transgressions will not prosper, but he who confesses and forsakes them will obtain mercy." Psalm 32:5 tells us of David's honesty with God about his sins, and its result. It says: "I acknowledged my sin to you, and I did not cover my iniquity; I said, 'I will confess my transgressions to the LORD,' and you forgave the iniquity of my sin." David found forgiveness for his adultery and murder. We, too, can find it if we have been false witnesses.
Second, we need to admit to the one or the ones about whom we have lied. This needs to be done, even if they have harmed us in some way.
Third, we must admit our wrong-doing to the ones who were told our lie or lies. Making amends for being a false witness will be a very humbling thing to do, and it can get very involved. But it must be done. We would want our name cleared of false charges, if it happened to us. Why would we do less for someone else? In Matthew 6:12, Jesus Christ said: "So whatever you wish that others would do to you, do also to them, for this is the Law and the Prophets."
What if we have been the victim of a false witness?
This can be a very painful thing. It is perfectly normal and acceptable to want our name cleared. We can even take steps to get it cleared. But we have to forgive the liar of their wrong-doing, even if they do not do anything to set the record straight.
Consider some Biblical statements that teach we must forgive those who have wronged us. In Matthew 6: 5 - 15, the Lord gave his disciples some instructions about prayer. In verse 12 he said we should ask God the Father to forgive our sins as we forgive those who have sinned against us. And then, after this model prayer was concluded, he returned to the subject of forgiving others and said: "For if you forgive others their trespasses (sins), your heavenly Father will also forgive you, but if you do not forgive others their trespasses, neither will your Father forgive your trespasses."
Ephesians 4:31 and 32 says: "Let all bitterness and wrath and anger and clamor and slander be put away from you, along with all malice. Be kind to one another, tenderhearted, forgiving one another as God in Christ forgave you." It is not always easy to forgive someone who has wronged us, but with the Lord's help it can be done. Philippians 4:13 says: "I can do all things through Christ who strengthens me." (New King James Version.) Preacher Stephen, about whom we read in Acts 7, is a good example of one who forgave his enemies. While he was being stoned to death by them simply because he preached the Gospel of Christ to them, he prayed a remarkable prayer. Acts 7:60 says: "And falling to his knees he cried out with a loud voice, 'Lord, do not hold this sin against them.' " May God help us to follow his example.
False witnesses must be forgiven and held accountable.
Other Biblical statements about false witnessing.
Christians aren't false witnesses about Jesus Christ.