Leviticus 19:16 (ESV)
You shall not go around as a slanderer among your people, and you shall not stand up against the life of your neighbor: I am the Lord.
Matthew 6:6-15 (NIV)
6But when you pray, go into your room, close the door and pray to your Father, who is unseen. Then your Father, who sees what is done in secret, will reward you.
7And when you pray, do not keep on babbling like pagans, for they think they will be heard because of their many words.
8Do not be like them, for your Father knows what you need before you ask him.
9"This, then, is how you should pray: " 'Our Father in heaven, hallowed be your name,
10your kingdom come, your will be done on earth as it is in heaven.
11Give us today our daily bread.
12Forgive us our debts, as we also have forgiven our debtors.
13And lead us not into temptation, but deliver us from the evil one. '
14For if you forgive men when they sin against you, your heavenly Father will also forgive you.
15But if you do not forgive men their sins, your Father will not forgive your sins.
Ephesians 4:29-32 (NIV)
29Do 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.
30And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption.
31Get rid of all bitterness, rage and anger, brawling and slander, along with every form of malice.
32Be kind and compassionate to one another, forgiving each other, just as in Christ God forgave you.