Matthew 15:18

but the things which go forth out of the mouth come out of the heart, and those defile man.

Matthew 12:34

Offspring of vipers! how can ye speak good things, being wicked? For of the abundance of the heart the mouth speaks.

Proverbs 15:2

The tongue of the wise useth knowledge aright; but the mouth of the foolish poureth out folly.

Proverbs 15:28

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

Matthew 15:11

Not what enters into the mouth defiles the man; but what goes forth out of the mouth, this defiles the man.

James 3:6-10

and the tongue is fire, the world of unrighteousness; the tongue is set in our members, the defiler of the whole body, and which sets fire to the course of nature, and is set on fire of hell.

1 Samuel 24:13

As saith the proverb of the ancients, Wickedness proceedeth from the wicked; but my hand shall not be upon thee.

Psalm 36:3

The words of his mouth are wickedness and deceit: he hath left off to be wise, to do good.

Proverbs 6:12

A man of Belial, a wicked person, is he that goeth about with a perverse mouth;

Proverbs 10:32

The lips of a righteous man know what is acceptable; but the mouth of the wicked is frowardness.

Luke 19:22

He says to him, Out of thy mouth will I judge thee, wicked bondman: thou knewest that I am a harsh man, taking up what I have not laid down and reaping what I have not sowed.

Revelation 13:5-6

And there was given to it a mouth, speaking great things and blasphemies; and there was given to it authority to pursue its career forty-two months.

Treasury of Scripture Knowledge

Summary

But those things which proceed out of the mouth come forth from the heart; and they defile the man.

Bible References

General references

Matthew 15:11
Not what enters into the mouth defiles the man; but what goes forth out of the mouth, this defiles the man.
Matthew 12:34
Offspring of vipers! how can ye speak good things, being wicked? For of the abundance of the heart the mouth speaks.
1 Samuel 24:13
As saith the proverb of the ancients, Wickedness proceedeth from the wicked; but my hand shall not be upon thee.
Psalm 36:3
The words of his mouth are wickedness and deceit: he hath left off to be wise, to do good.
Proverbs 6:12
A man of Belial, a wicked person, is he that goeth about with a perverse mouth;
Proverbs 10:32
The lips of a righteous man know what is acceptable; but the mouth of the wicked is frowardness.
Proverbs 15:2
The tongue of the wise useth knowledge aright; but the mouth of the foolish poureth out folly.
Luke 19:22
He says to him, Out of thy mouth will I judge thee, wicked bondman: thou knewest that I am a harsh man, taking up what I have not laid down and reaping what I have not sowed.
James 3:6
and the tongue is fire, the world of unrighteousness; the tongue is set in our members, the defiler of the whole body, and which sets fire to the course of nature, and is set on fire of hell.
Revelation 13:5
And there was given to it a mouth, speaking great things and blasphemies; and there was given to it authority to pursue its career forty-two months.