Matthew 15:19

For out of the heart proceed wicked thoughts, murder, adultery, fornication, theft, perjury, impiety of speech.

Acts 8:22

Repent, therefore, of this wickedness of yours, and pray to the Lord, in the hope that the purpose which is in your heart may perhaps be forgiven you.

Matthew 5:28

But I tell you that whoever looks at a woman and cherishes lustful thoughts has already in his heart become guilty with regard to her.

Matthew 9:4

Knowing their thoughts Jesus said, "Why are you cherishing evil thoughts in your hearts?

2 Corinthians 10:5

For we overthrow arrogant 'reckonings,' and every stronghold that towers high in defiance of the knowledge of God, and we carry off every thought as if into slavery--into subjection to Christ;

Treasury of Scripture Knowledge

Summary

The thought of foolishness is sin: and the scorner is an abomination to men.

Bible References

Thought

Matthew 5:28
But I tell you that whoever looks at a woman and cherishes lustful thoughts has already in his heart become guilty with regard to her.
Matthew 9:4
Knowing their thoughts Jesus said, "Why are you cherishing evil thoughts in your hearts?
Matthew 15:19
For out of the heart proceed wicked thoughts, murder, adultery, fornication, theft, perjury, impiety of speech.
Acts 8:22
Repent, therefore, of this wickedness of yours, and pray to the Lord, in the hope that the purpose which is in your heart may perhaps be forgiven you.
2 Corinthians 10:5
For we overthrow arrogant 'reckonings,' and every stronghold that towers high in defiance of the knowledge of God, and we carry off every thought as if into slavery--into subjection to Christ;