Proverbs 13:3 (ESV)

3 Whoever guards his mouth preserves his life; he who opens wide his lips comes to ruin.

A wise man will guard his mouth from saying words that will endanger his life. He will think twice before speaking so as to be cautious, about what he has to say. He will suppress speaking a harmful word and in doing so will preserve his life from saying something that will bring guilt and grief to him. The man who opens wide his mouth speaks without giving much thought to what he says. He does not engage his mind to think about and choose his words carefully which will result in him coming to ruin. His reputation will be harmed and his soul damaged because he has not guarded his heart from speaking harmful words.