James 3:6-8
The tongue also is a fire, a world of wickedness among the parts of the body. It pollutes the whole person, sets the course of his life on fire, and is itself set on fire by hell. / All kinds of animals, birds, reptiles, and creatures of the sea are being tamed and have been tamed by man, / but no man can tame the tongue. It is a restless evil, full of deadly poison.

Romans 3:13-14
“Their throats are open graves; their tongues practice deceit.” “The venom of vipers is on their lips.” / “Their mouths are full of cursing and bitterness.”

Proverbs 6:16-19
There are six things that the LORD hates, seven that are detestable to Him: / haughty eyes, a lying tongue, hands that shed innocent blood, / a heart that devises wicked schemes, feet that run swiftly to evil, ...

Matthew 12:34-35
You brood of vipers, how can you who are evil say anything good? For out of the overflow of the heart the mouth speaks. / The good man brings good things out of his good store of treasure, and the evil man brings evil things out of his evil store of treasure.

Jeremiah 9:3-8
“They bend their tongues like bows; lies prevail over truth in the land. For they proceed from evil to evil, and they do not take Me into account,” declares the LORD. / “Let everyone guard against his neighbor; do not trust any brother, for every brother deals craftily, and every friend spreads slander. / Each one betrays his friend; no one tells the truth. They have taught their tongues to lie; they wear themselves out committing iniquity. ...

Ephesians 4:31
Get rid of all bitterness, rage and anger, outcry and slander, along with every form of malice.

Proverbs 10:18
The one who conceals hatred has lying lips, and whoever spreads slander is a fool.

1 Peter 3:10
For, “Whoever would love life and see good days must keep his tongue from evil and his lips from deceitful speech.

Psalm 64:3-4
who sharpen their tongues like swords and aim their bitter words like arrows, / ambushing the innocent in seclusion, shooting suddenly, without fear.

Proverbs 12:18
Speaking rashly is like a piercing sword, but the tongue of the wise brings healing.

Matthew 15:18-19
But the things that come out of the mouth come from the heart, and these things defile a man. / For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false testimony, and slander.

Psalm 52:2-4
Your tongue devises destruction like a sharpened razor, O worker of deceit. / You love evil more than good, falsehood more than speaking truth. Selah / You love every word that devours, O deceitful tongue.

Proverbs 16:27
A worthless man digs up evil, and his speech is like a scorching fire.

Luke 6:45
The good man brings good things out of the good treasure of his heart, and the evil man brings evil things out of the evil treasure of his heart. For out of the overflow of the heart the mouth speaks.

Psalm 55:21
His speech is smooth as butter, but war is in his heart. His words are softer than oil, yet they are swords unsheathed.