Out of the abundance of the heart the mouth speaks. 

Let the word of Christ dwell in you richly in all wisdom.Keep your heart with all diligence, for out of it spring the issues of life. § Death and life are in the power of the tongue. § The mouth of the righteous speaks wisdom, and his tongue talks of justice. The law of his God is in his heart; none of his steps shall slide. § Let no corrupt word proceed out of your mouth, but what is good for necessary edification, that it may impart grace to the hearers.For we cannot but speak the things which we have seen and heard. § I believed, therefore I spoke.Whoever confesses Me before men, him I will also confess before My Father who is in heaven. § With the heart one believes unto righteousness, and with the mouth confession is made unto salvation.