Bitterness / Unforgiveness 

Create in me a clean heart, O God, and renew a right spirit within me.

Psalm 51:10

For if you forgive others their trespasses, your heavenly Father will also forgive you, but if you do not forgive others their trespasses, neither will your Father forgive your trespasses.

Matthew 6:14-15

Be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you.

Ephesians 4:32

See to it that no one fails to obtain the grace of God; that no “root of bitterness” springs up and causes trouble, and by it many become defiled…

Hebrews 12:15

Unless noted all scripture references are taken from the English Standard Version (ESV) of the Bible.