Matthew 12:34-35
You brood of vipers! How can you, wicked as you are, say anything that is good? For the mouth talks about the things that fill the heart.
Luke 6:45
The good man, out of his good inner storehouse, brings forth what is good, the bad man, out of his bad one, what is bad. For a man's mouth usually speaks the things that fill his heart.
Matthew 15:19
For out of the heart come evil thoughts, murder, adultery, immorality, stealing, false witnessing, irreverent speech.
Mark 7:21-23
for from the inside, that is, from the hearts of men, designs for doing evil come, sexual immorality, stealing, murder,
Mark 14:38
You must all keep watching and praying that you may not be exposed to temptation. Man's spirit is willing but human nature is weak."
Hebrews 12:15
Continue to look after one another, that no one fails to gain God's spiritual blessing; or some evil like a bitter root may spring up and trouble you, and many of you be contaminated by it --
James 1:14-15
But anyone is tempted to do evil when he is allured by his own evil desire and enticed by a bait.