Matthew 12:34-35

"You generation of vipers! How can you speak good, when you are evil? For the mouth speaks what the heart is full of. "When the time of fruit drew near, he sent his slaves to the vine-dressers seized to get his fruit.

Luke 6:45

"The good man out of the good treasure-house of his heart brings forth good; and the evil man out of the evil treasure-house of his heart brings forth evil; for the mouth speaks out of the abundance of the heart.

Matthew 15:19

For out of the heart come forth evil thoughts, murder, adultery, unchastity, theft, perjury, slander.

Mark 7:21-23

From within, from the heart of man, proceed evil purposes??22 fornication, theft, murder, adultery, greed, malice, deceit, wantonness, envy, slander, arrogance, reckless folly??23 all these wicked things issue from within and defile a man."

Mark 14:38

Keep watch, all of you, and pray that you may not come into temptation; the spirit is willing, but the flesh is weak.'

Hebrews 12:15

Look carefully that there be no one who falls back from the grace of God; that no root of bitterness springs up to trouble you, and by its means many become defiled.

James 1:14-15

But each man is tempted by his own lusts that allure and entice him.

Treasury of Scripture Knowledge

Summary

Keep thy heart with all diligence; for out of it are the issues of life.

Bible References

Keep

Mark 14:38
Keep watch, all of you, and pray that you may not come into temptation; the spirit is willing, but the flesh is weak.'
Hebrews 12:15
Look carefully that there be no one who falls back from the grace of God; that no root of bitterness springs up to trouble you, and by its means many become defiled.

For

Matthew 12:35
"A good man out of his good treasure brings forth good; and from his evil treasure a bad man brings out evil.
Matthew 15:19
For out of the heart come forth evil thoughts, murder, adultery, unchastity, theft, perjury, slander.
Mark 7:21
From within, from the heart of man, proceed evil purposes??22 fornication, theft, murder, adultery, greed, malice, deceit, wantonness, envy, slander, arrogance, reckless folly??23 all these wicked things issue from within and defile a man."
James 1:14
But each man is tempted by his own lusts that allure and entice him.