James 3:3-4 Behold, we put bits in the horses' mouths, that they may obey us; and we turn about their whole body.  Behold also the ships, which though they be so great, and are driven of fierce winds, yet are they turned about with a very small helm, whithersoever the governor listeth.

This is a verse about the human tongue.  Note that the horses, strong as they are, can be controlled by the mouth.  The tongue is compared to the helm of a ship that controls a huge ship that is driven by fierce winds.  The implication is that the tongue controls the whole being.  We must learn to yield our tongues, our speach, to the Holy Spirit.

Romans 6:13 Neither yield ye your members as instruments of unrighteousness to sin: but yield yourselves to God, as those that are alive from the dead, and your members as instruments of righteousness to God.