Philippians 4:6-7 (NIV)
Do not be anxious about anything, but in every situation, by prayer and petition, with thanksgiving, present your requests to God. 7 And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus. 

Ephesians 4:29-32 (NIV)
Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen. 30 And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption. 31 Get rid of all bitterness, rage and anger, brawling and slander, along with every form of malice. 32 Be kind and compassionate to one another, forgiving each other, just as in Christ God forgave you. 

Matthew 12:36 (NLT)
And I tell you this, you must give an account on judgment day for every idle word you speak. 

Matthew 5:21-22 (NIV)
You have heard that it was said to the people long ago, ‘You shall not murder, and anyone who murders will be subject to judgment.’ 22 But I tell you that anyone who is angry with a brother or sister will be subject to judgment. Again, anyone who says to a brother or sister, ‘Raca,’ is answerable to the court. And anyone who says, ‘You fool!’ will be in danger of the fire of hell. 

Matthew 5:21-22 (MSG)
You’re familiar with the command to the ancients, ‘Do not murder.’ I’m telling you that anyone who is so much as angry with a brother or sister is guilty of murder. Carelessly call a brother ‘idiot!’ and you just might find yourself hauled into court. Thoughtlessly yell ‘stupid!’ at a sister and you are on the brink of hellfire. The simple moral fact is that words kill.