Matthew 12:34-35

Offspring of vipers, how can you, being evil, speak good things? For out of the abundance of the heart the mouth speaks.

Luke 6:45

The good man out of the good treasury of his heart brings forth good, and the evil man out of the evil brings forth evil; for out of the abundance of the heart its mouth speaks.

Matthew 15:19

For from the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false testimonies, blasphemies:

Mark 7:21-23

for from within, from the hearts of men, proceed evil thoughts, fornications,

Mark 14:38

Watch and pray that you enter not into trial; the spirit indeed is willing, but flesh is weak.

Hebrews 12:15

taking care that no one may come short of the grace of God, that no root of bitterness springing up may make trouble and by it many be defiled,

James 1:14-15

But every one is tempted when he is drawn away by his desires, and enticed;

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
Watch and pray that you enter not into trial; the spirit indeed is willing, but flesh is weak.
Hebrews 12:15
taking care that no one may come short of the grace of God, that no root of bitterness springing up may make trouble and by it many be defiled,

For

Matthew 12:35
The good man, out of his good treasury, casts forth good things; and the evil man, out of his evil treasury, casts forth evil things.
Matthew 15:19
For from the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false testimonies, blasphemies:
Mark 7:21
for from within, from the hearts of men, proceed evil thoughts, fornications,
James 1:14
But every one is tempted when he is drawn away by his desires, and enticed;