James 1:26

26 If anyone thinks himself to be religious, yet does not bridle his tongue but deceives his own heart, this person’s religion is worthless.

Luke 6:43-45 NLT

The Tree and Its Fruit

43 “A good tree can’t produce bad fruit, and a bad tree can’t produce good fruit. 44 A tree is identified by its fruit. Figs are never gathered from thornbushes, and grapes are not picked from bramble bushes. 45 A good person produces good things from the treasury of a good heart, and an evil person produces evil things from the treasury of an evil heart. What you say flows from what is in your heart.

Proverbs 4:23

23 Guard your heart above all else,for it determines the course of your life.

Proverbs 18:21 Death and life are in the power of the tongue, And those who love it will eat its fruit.

Matthew 15:11

New Living Translation

11 It’s not what goes into your mouth that defiles you; you are defiled by the words that come out of your mouth.”

Hebrews 4:12

12 For the word of God is living and powerful, and sharper than any two-edged sword, piercing even to the division of soul and spirit, and of joints and marrow, and is a discerner of the thoughts and intents of the heart.