1 Peter 3:15

Revere the Christ as Lord in your hearts; always ready to give an answer to any one who asks your reason for the hope that you cherish, but giving it humbly and in all reverence,

Matthew 12:34

You brood of vipers! how can you, evil as you are, say anything good? For what fills the heart will rise to the lips.

Titus 1:10-11

There are, indeed, many unruly persons--great talkers who deceive themselves, principally converts from Judaism,

James 3:6-8

And the tongue is like a spark. Among the members of our body it proves itself a very world of mischief; it contaminates the whole body; it sets the wheels of life on fire, and is itself set on fire by the flames of the Pit.

2 Peter 2:18

With boastful and foolish talk, they appeal to the passions of man's lower nature, and, by their profligacy, entice those who are just escaping from the men who live such misguided lives.

Treasury of Scripture Knowledge

Summary

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

Heart

General references

Bible References

Heart

1 Peter 3:15
Revere the Christ as Lord in your hearts; always ready to give an answer to any one who asks your reason for the hope that you cherish, but giving it humbly and in all reverence,

General references

Matthew 15:18
But the things that come out from the mouth proceed from the heart, and it is these that defile a man;