Charles H. Spurgeon on Psalms 119:80

Let my heart be sound. What is a sound heart? It notes reality and solidity in grace. The Septuagint hath it, Let my heart be without spot and blemish. It implies the reality of grace, opposed to the bare form of godliness, or the fair shows of hypocrites, and the sudden and vanishing motions of temporaries.

If you would have me unfold what this sound heart is, there is required these four things:

1. An enlightened understanding; that is, the directive part of the soul; and it is sound when it is kept free from the leaven and contagion of error: "A man of understanding walketh uprightly, " Proverbs 15:21. A sound mind is a good help to a sound heart.

2. There is required an awakened conscience, that warns of our duty, and riseth up in dislike of sin upon all occasions: "When thou goest, it shall lead thee; when thou sleepest, it shall keep thee; and when thou awakest, it shall talk with thee" (Proverbs 6:22): to have a constant monitor in our bosoms to put us in mind of God, when our reins preach to us in the night season (Psalms 16:7): there is a secret spy in our bosoms that observes all that we do, and think, and speak; a domestic chaplain, that is always preaching to us. His heart is his Bible.

3. There is required a rightly disposed will, or a steadfast purpose to walk with God in all conditions, and to do what is good and acceptable in his sight: "He exhorted them all that with purpose of heart they would cleave unto the Lord, "Acts 6:23. Many have light inclinations, or wavering resolutions; but their hearts are not fixedly, habitually bent to please God; therein chiefly lieth this sound heart, that it doth inseparably cleave to God in all things.

4. There is required that the affections be purged and quickened: these are the vigorous motions of the will, and therefore this must be heedfully regarded; purged they must be from that carnality and fleshliness that cleaveth to them. This is called in Scripture the circumcision of the heart (Deuteronomy 30:6). Condensed from Manton.