A gentle response defuses anger, but a sharp tongue kindles a temper-fire.
Proverbs 15:1 MSG
The first verse of this Proverb introduces a theme that runs throughout the chapter; it tells us that not only what we say matters, but how we say it. We can spread knowledge, be a tree of life, act as peacemakers, and a whole lot more - or as James 3:6 says, it can be a fire of destruction.
We shouldn't confuse encouraging speech with glossing over the truth or not saying what needs to be said. This Proverb points out that at the same time the wise person seeks out, even invites correction. He or she seeks the counsel of many wise counsellors and makes it a habit to listen to the wise.
I see Jesus as a master of the power of positive speech. This isn't to say that he backed away from the difficult things to say, nor that he never needed to confront, but In world that is full of negative, life-sapping speech, part of the attraction He had with others was this quality. That's how we as His followers are encouraged to be; that's part of the "aroma of Christ" that we are to spread (2 Cor. 2:15).