This is something that I have been working on with my 7-year old son. And then, this morning, I read these words in Jesus Calling by Sarah Young...
"Words have such great power to bless or to wound. When you speak carelessly or negatively, you damage others as well as yourself. This ability to verbalize is an awesome privilege, granted only to those I created in My image. You need help in wielding this mighty power responsibly."
Proverbs 12:18 (New King James Version)
There is one who speaks like the piercings of a sword,
But the tongue of the wise promotes health.
James 1:19 (New International Version)
My dear brothers, take note of this: Everyone should be quick to listen, slow to speak and slow to become angry,
Ephesians 4:29 (New International Version)
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.