Don't use foul or abusive language. Let everything you say be good and helpful, so that your words will be an encouragement to those who hear them. - Ephesians 4:29 (NLT)  

Stay away from fools, for you won't find knowledge on their lips. - Proverbs 14:7 (NLT)

Don't befriend angry people or associate with hot-tempered people,- Proverbs 22:24 (NLT)

The heartfelt counsel of a friend is as sweet as perfume and incense. - Proverbs 27:9 (NLT)

Don't be fooled by those who say such things, for "bad company corrupts good character" - 1 Corinthians 15:33 (NLT)

A friend is always loyal, and a brother is born to help in time of need. - Proverbs 17:17 (NLT)

There are "friends" who destroy each other, but a real friend sticks closer than a brother. - Proverbs 18:24 (NLT)