Ecclesiastes

Ecclesiastes 5:2  "Be not rash with thy mouth, and let not thine heart be hasty to utter any thing before God: for God is in heaven, and thou upon earth: therefore let thy words be few."

What great advice!  God can see a whole lot more from heaven than we can see from earth.  Why should we think we know better than He?

Ecclesiastes 7:21-22  "Also take no heed unto all words that are spoken; lest thou hear thy servant curse thee:  For oftentimes also thine own heart knoweth that thou thyself likewise hast cursed others." 

This one isn't often quoted, but should be!  It is perfect for forgiving.  The perfect example of having a beam in our own eye and trying to remove a mote from another.  The reminder that we ourselves are not perfect and are in need of mercy so we need to also extend mercy to others.