Answer
Psalm 101:5
Whoever slanders his neighbor secretly I will destroy. Whoever has a haughty look and an arrogant heart I will not endure.
Matthew 12:36
I tell you, on the day of judgment people will give account for every careless word they speak,
1 Peter 3:16
Having a good conscience, so that, when you are slandered, those who revile your good behavior in Christ may be put to shame.
Proverbs 10:18
The one who conceals hatred has lying lips, and whoever utters slander is a fool.
James 4:11
Do not speak evil against one another, brothers. The one who speaks against a brother or judges his brother, speaks evil against the law and judges the law. But if you judge the law, you are not a doer of the law but a judge.
2 Timothy 3:1-5
But understand this, that in the last days there will come times of difficulty. For people will be lovers of self, lovers of money, proud, arrogant, abusive, disobedient to their parents, ungrateful, unholy, heartless, unappeasable, slanderous, without self-control, brutal, not loving good, treacherous, reckless, swollen with conceit, lovers of pleasure rather than lovers of God, having the appearance of godliness, but denying its power. Avoid such people.
Exodus 20:16
You shall not bear false witness against your neighbor.
Titus 3:2
To speak evil of no one, to avoid quarreling, to be gentle, and to show perfect courtesy toward all people.
Matthew 5:11
Blessed are you when others revile you and persecute you and utter all kinds of evil against you falsely on my account.
1 Peter 2:1
So put away all malice and all deceit and hypocrisy and envy and all slander.
Proverbs 16:28
A dishonest man spreads strife, and a whisperer separates close friends.
Ephesians 4:31-32
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.
Luke 6:45
The good person out of the good treasure of his heart produces good, and the evil person out of his evil treasure produces evil, for out of the abundance of the heart his mouth speaks.
Proverbs 20:19
Whoever goes about slandering reveals secrets; therefore do not associate with a simple babbler.
Psalm 109:3
They encircle me with words of hate, and attack me without cause.
Exodus 23:1
You shall not spread a false report. You shall not join hands with a wicked man to be a malicious witness.
Proverbs 11:9
With his mouth the godless man would destroy his neighbor, but by knowledge the righteous are delivered.
Mark 7:20-23
And he said, “What comes out of a person is what defiles him. For from within, out of the heart of man, come evil thoughts, sexual immorality, theft, murder, adultery, coveting, wickedness, deceit, sensuality, envy, slander, pride, foolishness. All these evil things come from within, and they defile a person.”
James 1:12
Blessed is the man who remains steadfast under trial, for when he has stood the test he will receive the crown of life, which God has promised to those who love him.
Ephesians 4:32
Be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you.
Unless otherwise noted, all Bible verses are from The Holy Bible, English Standard Version® Copyright© 2001 by Crossway Bibles, a publishing ministry of Good News Publishers.
Special thanks to OpenBible.info for the data on the most well-known Bible verses.