Proverbs 12:5 (ESV) … “The thoughts of the righteous are just; the counsels of the wicked are deceitful.”
1. The word of God is a discerner of the thoughts and intents of the heart, and judges them. We mistake if we imagine that thoughts are free. No, they are under the divine cognizance, and therefore under the divine command.
2. We ought to be observers of the thoughts and intents of our own hearts, and to judge of ourselves by them; for they are the first-born of the soul, that have most of its image undisguised. Right thoughts are a righteous man’s best evidences, as nothing more certainly proves a man wicked than wicked contrivances and designs. A good man may have in his mind bad suggestions, but he does not indulge them and harbour them till they are ripened into bad projects and resolutions.
3. It is a man’s honour to mean honestly, and to have his thoughts right, though a word or action may be misplaced, or mistimed, or at least misinterpreted. But it is a man’s shame to lie always at catch, to act with deceit, with trick and design, not only with a long reach, but with an overreach. 
 Henry, M. (1994). Matthew Henry’s commentary on the whole Bible: complete and unabridged in one volume (p. 980). Peabody: Hendrickson.