Proverbs 17:28 - "Even fools are thought wise when they keep silent; with their mouths shut, they seem intelligent."
I've said some really dumb things in my life I wish I could take back. As a matter of fact I still often do. The truth is though... You can't take them back. What's said is said. You can apologize and ask for forgiveness but far better than that is to just not to say selfish harmful things in the first place. Wisdom is not a mouth full of big words babbling on and on about a subject full of your own opinion. Wisdom is like chosen gold, pearls or diamonds. You don't just flash them about everywhere and to just anyone. You choose the right time, the right place and the right people. Be wise, learn to control your tongue and you'll save yourself and others a lot of pain and suffering. Choose to actively say no to gossip, slander, lies, accusation and hate and instead choose to let your tongue be used to build up, encourage, speak faith, life and light. God loves you.
[ Ephesians 4:29 - Let no corrupting talk come out of your mouths, but only such as is good for building up, as fits the occasion, that it may give grace to those who hear. ]