The most dangerous, most sin prone member of our bodies is not what most people would think, unless they were thinking of their tongue. That makes speech our most dangerous, most sin prone activity, and it makes silence our greatest safeguard against those sins. Just think of the list: slander, lies, cursing, swearing, blasphemy, gossip, tale bearing, and verbosity. With our tongue we express judgements and break confidences.
This assessment is consistent with Scripture.
And the tongue is a fire, a world of unrighteousness. The tongue is set among our members, staining the whole body, setting on fire the entire course of life, and set on fire by hell. James 3:6 (ESV)
As goes our tongue, so goes our whole body. As goes our body, so goes our life.
Happy is the man who can control his tongue; even happier is the man who feels little need to use it. God bless the man who so values silence that when he does speak it is only to bless and edify.