12 So he answered and said, “Must I not take heed to speak what the LORD has put in my mouth?” (Numbers 23:12)
Jesus said, "Out of the abundance of the heart the mouth speaks." King David penned the words, "Wherewithal shall a young man cleanse his way; by taking head to Thy Word. ... Thy Word have I hid in my heart, that I may not sin against Thee." Else where it is written, "As a man thinks in his heart, so is he."
The words that are entertained in the heart will eventually find their expression with the mouth, and Jesus again said, "By your words you shall be justified, and by your words you shall be condemned."
It really does matter what we believe, it really does matter what we say, and it really does matter how we express those words we believe and say in our actions.
As a teacher I heard children use inappropriate language. When I corrected them, many would say to me, "But I didn't mean it." My response was, "You only said what was truly in your heart. Your heart is unclean, and it needs to be changed by God."
I hear many Christians, who claim to be followers of the Lord Jesus Christ, but whose mouths reveal an unclean, godless heart. If, for example, as a Christian we advocate a woman's right to abortion, in the name of love for the woman, our mouth reveals that our heart is full of murder; if we advocate acceptance of homosexuality as a legitimate expression of sexuality, in the name of tolerance, our mouth reveals that our heart is full of adultery; if we advocate debt financing of lifestyle, in the name of a quality of life, then our mouth reveals a heart full of covetousness. Jesus says that murderers, adulterers and covetous people will not enter the kingdom of God; such people shall be cast out.
God's prophets are not popular, and they are not warmly received in any age. A prophet has the Word of God so full and burning in his heart that he cannot but speak what the Lord has put in his mouth; even in the face of an angry king.
O Lord, continue to help me to hide Your Word in my heart, and let my mouth be filled with the words you give me to speak. Let me proclaim Your righteousness, not with a sense of moral superiority, but with a holy fear that God is no respecter of persons: "the soul that sins must die." Teach me to humble myself, confess my sins, and submit myself to the washing of the water by the Word.