Proverbs 4:23 (KJV)
23 Keep thy heart with all diligence; for out of it are the issues of life.
Proverbs 4:23 (NLT)
23 Above all else, guard your heart, for it affects everything you do.
Be ye angry, and sin not: let not the sun go down upon your wrath:
27 Neither give place to the devil.
31 Let all bitterness, and wrath, and anger, and clamour, and evil speaking, be put away from you, with all malice:
32 And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ’s sake hath forgiven you.
Matthew 18:23-35 (NIV)
23 “Therefore, the kingdom of heaven is like a king who wanted to settle accounts with his servants.
24 As he began the settlement, a man who owed him ten thousand bags of gold was brought to him.
25 Since he was not able to pay, the master ordered that he and his wife and his children and all that he had be sold to repay the debt.
26 “At this the servant fell on his knees before him. ‘Be patient with me,’ he begged, ‘and I will pay back everything.’ 27 The servant’s master took pity on him, canceled the debt and let him go.
28 “But when that servant went out, he found one of his fellow servants who owed him a hundred silver coins. He grabbed him and began to choke him. ‘Pay back what you owe me!’ he demanded.
29 “His fellow servant fell to his knees and begged him, ‘Be patient with me, and I will pay it back.’
30 “But he refused. Instead, he went off and had the man thrown into prison until he could pay the debt.
31 When the other servants saw what had happened, they were outraged and went and told their master everything that had happened.
32 “Then the master called the servant in. ‘You wicked servant,’ he said, ‘I canceled all that debt of yours because you begged me to.
33 Shouldn’t you have had mercy on your fellow servant just as I had on you?’
34 In anger his master handed him over to the jailers to be tortured, until he should pay back all he owed.
35 “This is how my heavenly Father will treat each of you unless you forgive your brother or sister from your heart.”