Make your ear attentive to wisdom and incline your heart to understanding to understand the fear of the Lord and find the knowledge of God. (Proverbs 2:2, 2:5)
The LORD hates a heart that devises wicked plans
A heart that devises wicked plans is one of the six things that the LORD hates, seven that are an abomination to him. (Proverbs 6:16-19)
What proceeds from the heart out of the mouth defiles a person
Jesus teaches any evil proceeding from the heart out of the mouth defiles a person. "For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander. These are what defile a person."