Heart
Matthew 18:35 (KJV)
So likewise shall my heavenly Father do also unto you, if ye from your hearts forgive not every one his brother their trespasses.
God will strengthen our hearts, let us trust Him.
Psalm 27:14 (KJV)
14 Wait on the Lord: be of good courage, and he shall strengthen thine heart: wait, I say, on the Lord.
Luke 1:17 (KJV)
And he shall go before him in the spirit and power of Elias, to turn the hearts of the fathers to the children, and the disobedient to the wisdom of the just; to make ready a people prepared for the Lord.
John 14:27 (KJV)
Peace I leave with you, my peace I give unto you: not as the world giveth, give I unto you. Let not your heart be troubled, neither let it be afraid.
Psalm 37:4 (KJV)
Delight thyself also in the Lord: and he shall give thee the desires of thine heart.
2 Corinthians 4:6 (KJV)
For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ.
God knows the heart of man
Matthew 9:4 (KJV)
And Jesus knowing their thoughts said, Wherefore think ye evil in your hearts?
Matthew 12:34 (KJV)
O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh.
Our hearts guide our mouth and actions
Matthew 12:35 (KJV)
A good man out of the good treasure of the heart bringeth forth good things: and an evil man out of the evil treasure bringeth forth evil things.
Luke 6:45 (KJV)
A good man out of the good treasure of his heart bringeth forth that which is good; and an evil man out of the evil treasure of his heart bringeth forth that which is evil: for of the abundance of the heart his mouth speaketh.
Luke 12:34 (KJV)
For where your treasure is, there will your heart be also.
Romans 2:15 (KJV)
Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another;)
Romans 10:9 (KJV)
That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.