Proverbs 15:28

The heart of the righteous ponders how to answer,
But the mouth of the wicked pours out evil things.

1 Peter 3:15

but sanctify Christ as Lord in your hearts, always being ready to make a defense to everyone who asks you to give an account for the hope that is in you, yet with gentleness and reverence;

Proverbs 15:2

The tongue of the wise makes knowledge acceptable,
But the mouth of fools spouts folly.

1 Kings 3:23-28

Then the king said, “The one says, ‘This is my son who is living, and your son is the dead one’; and the other says, ‘No! For your son is the dead one, and my son is the living one.’”

Proverbs 10:19

When there are many words, transgression is unavoidable,
But he who restrains his lips is wise.

Proverbs 13:16

Every prudent man acts with knowledge,
But a fool displays folly.

Proverbs 16:23

The heart of the wise instructs his mouth
And adds persuasiveness to his lips.

Proverbs 29:11

A fool always loses his temper,
But a wise man holds it back.

Proverbs 29:20

Do you see a man who is hasty in his words?
There is more hope for a fool than for him.

Ecclesiastes 5:2

Do not be hasty in word or impulsive in thought to bring up a matter in the presence of God. For God is in heaven and you are on the earth; therefore let your words be few.

Ecclesiastes 5:6

Do not let your speech cause you to sin and do not say in the presence of the messenger of God that it was a mistake. Why should God be angry on account of your voice and destroy the work of your hands?

Ecclesiastes 10:12-14

Words from the mouth of a wise man are gracious, while the lips of a fool consume him;

Matthew 12:34

You brood of vipers, how can you, being evil, speak what is good? For the mouth speaks out of that which fills the heart.

Titus 1:10-11

For there are many rebellious men, empty talkers and deceivers, especially those of the circumcision,

James 3:6-8

And the tongue is a fire, the very world of iniquity; the tongue is set among our members as that which defiles the entire body, and sets on fire the course of our life, and is set on fire by hell.

2 Peter 2:18

For speaking out arrogant words of vanity they entice by fleshly desires, by sensuality, those who barely escape from the ones who live in error,

Treasury of Scripture Knowledge

Summary

The heart of the righteous studieth to answer: but the mouth of the wicked poureth out evil things.

General references

Bible References

Heart

Proverbs 15:2
The tongue of the wise makes knowledge acceptable,
But the mouth of fools spouts folly.
Proverbs 16:23
The heart of the wise instructs his mouth
And adds persuasiveness to his lips.
1 Kings 3:23
Then the king said, “The one says, ‘This is my son who is living, and your son is the dead one’; and the other says, ‘No! For your son is the dead one, and my son is the living one.’”
Ecclesiastes 5:2
Do not be hasty in word or impulsive in thought to bring up a matter in the presence of God. For God is in heaven and you are on the earth; therefore let your words be few.
1 Peter 3:15
but sanctify Christ as Lord in your hearts, always being ready to make a defense to everyone who asks you to give an account for the hope that is in you, yet with gentleness and reverence;

General references

Proverbs 14:33
Wisdom rests in the heart of one who has understanding,
But in the hearts of fools it is made known.
Matthew 15:18
But the things that proceed out of the mouth come from the heart, and those defile the man.