Richard Sibbes reminds us of the importance of not only speaking the truth, but thinking and meditating on the truth. This is the work and manifestation of a righteous man — one who speaks the truth in his heart:
All sin is either from false principles, or ignorance, or thoughtlessness, or unbelief of what is true.…It is good, therefore, to store up true principles in our hearts, and to refresh them often, that, in virtue of them, our affections and actions may be more vigorous. [The Bruised Reed]
Words of Grace 