Bearing false witness is mentioned many times in the Bible, exclusively as something bad. “You shall not bear false witness against your neighbor” is the ninth of the Ten Commandments that Moses brought back with him from his encounter with God on Mount Sinai (Exodus 20:16). False witness, or spreading a false report, is associated with being allied with the wicked (Exodus 23:1), willing to do violence to others (Psalm 27:12), and sowing discord among brothers (Proverbs 6:19). The Bible calls bearing false witness lying (Proverbs 14:5) and compares a man who bears false witness against his neighbor to a violent weapon (Proverbs 25:18). Lies harm people.
A false witness is one who stands up and swears before others that something untrue is true, especially with the intention of hurting someone else or ruining his reputation. This happened to David (Psalm 27:12), Jesus (Matthew 26:60; Mark 14:56), and Stephen (Acts 6:13). When the wicked Queen Jezebel wished to procure a vineyard for her sulking husband, King Ahab, she employed two false witnesses. Naboth, the rightful owner of the vineyard, was seated in an honorable place on a day of fasting, but “then two scoundrels came and sat opposite him and brought charges against Naboth before the people, saying, ‘Naboth has cursed both God and the king.’ So they took him outside the city and stoned him to death” (1 Kings 21:13). What the “scoundrels” said against Naboth was absolutely untrue; they were bearing false witness with impunity and with the queen’s blessing. As a result, an innocent man was killed. When a person is righteous and his enemies can find nothing with which to blame him, bearing false witness is a common weapon.
The lies told by a false witness come from the sinful human heart—along with murder, adultery, sexual immorality, theft, slander, and evil thoughts (Matthew 15:19). Jesus said that man is defiled by these evil things that come from the heart. The only possible cure for an evil heart that bears false witness is to receive a new, pure heart, which can only be given by God (Ezekiel 36:26). When a person is indwelt by the Holy Spirit, he will be like a fresh spring or a fruitful tree or a budding vine, bursting with good things (John 7:38; Psalm 1:1–6; John 15:4–5). The old is gone, and the new takes its place (Ephesians 4:22–24). Those who are in Christ have a new heart that speaks the truth: “Each of you must put off falsehood and speak truthfully to your neighbor” (Ephesians 4:25). A person who bears false witness is controlled by the flesh rather than by the Spirit of God, and he should repent of that sin and turn to Christ.
"There are six things that the Lord hates, seven that are an abomination to Him...a lying tongue...a false witness who breathes out lies..." (Proverbs 6:16–19).