The verse that stands out for me in Prov 12 is verse 25:
v25: Anxiety in the heart of man causes depression, but a good/encouraging word makes the heart glad.
Being a relatively new blogger I find it amazing how happy I am when people leave comments. I suppose, because of the nature of the blog and those I seek out (specifically Christian women's blogs), the nature and content of the comments are positive.
The lesson in this for me is that a gentle word, a positive word, can have a huge impact especially on people who are depressed or going through some personal crisis. If positive words have such an impact on somebody, imagine the impact of negative words!
The bible says much about words. In this chapter alone:
v6 says: The words of the wicked are like a murderous ambush, but the words of the godly SAVE LIVES.
v13: The wicked are trapped by their own words, but the godly escape such trouble.
v14(a): People can get many good things by the words they say.
v18: Some people make cutting remarks, but the words of the wise BRING HEALING.
v25: Anxiety in the heart of man causes depression, but a good word makes the heart glad.
There are many many other scriptures in Proverbs alone that refer to words and their use for good or evil.
I know the use of my words are something I have to work on constantly. My encouragement to you is to look for opportunities to speak positively to someone. You may just make their day. And the added benefit to you is inner peace and joy.
Use your words to God's glory.
(Ps: I hope my Mom's sage words don't put you off commenting!)