There are many scriptures that deal with how we use our words:
I really like that scripture because it says 2 things to me. 1stly, I must muzzle my mouth which implies I must bite my tongue even though there is so much to be said!!! and 2ndly, what is my witness in front of those who do not know the Lord as their personal saviour. Which leads me to the scripture right on top, with all this knowledge, if we are wise (or trying ever so hard to be so) we would use this knowledge rightly.