Our Scripture reading today is Psalm 39:1-3.
Verse 1, " I said, I will take heed to my ways, that I sin not with my tongue: I will keep my mouth with a bridle, while the wicked is before me."
It is almost impossible to take words back that have already been uttered.  No doubt we all have some words that we wish we had not said.  How many times did we speak before we thought?  I would say that is not the moment to "think".  I need to "think" ahead of time by asking the Holy Spirit to guide my thoughts and words.  When we are filled with the Spirit, there will not be any regrets over something we said to our spouse, children, or church member.
On the flip side of the coin, I am sure there are times when we should have said something and we did not.  How about when the Spirit is leading us to share a Gospel tract or our testimony and we let the fear of man take over?  Could this also be considered sinning with our tongue?  We should have been obedient to use our voice to proclaim the message of hope.  
Either way, I would like us to see that the tongue is capable of damaging and encouraging at the same time.  James 3:10, "Out of the same mouth proceedeth blessing and cursing. My brethren, these things ought not so to be."  It must be controlled by God's Spirit!