Let my heart be sound in thy statutes Having, a little before, desired to be endued with a sound understanding, he now prays, in a similar manner, for sincere affection of heart. The understanding and affections, as is well known, are the two principal faculties of the human soul, both of which he clearly shows to be depraved and perverse, when he requests that his understanding may be illuminated, and, at the same time, that his heart may be framed to the obedience of the law. This plainly refutes all that the Papists babble about free will. The prophet not only here prays that God would help him, because his will was weak; but he testifies, without qualification, that uprightness of heart is. the gift of the Holy Spirit. We are, moreover, taught by these words, in what the true keeping of the law consists. A great part of mankind, after having carelessly framed their life according to the Divine law, by outward obedience, think that they want nothing. But the Holy Spirit here declares that no service is acceptable to God, except that which proceeds from integrity of heart. As to the word, tmym, thamim, rendered sound, we have elsewhere said, that a sound heart is set in opposition to a double or deceitful heart. It is as if the prophet had said, that those who are without dissimulation, and who offer to God a pure heart, yield themselves truly to Him. When it is added, that I may not be put to shame, it is intimated, that such shall be the undoubted issue as to all the proud, who, disdaining the grace of God, lean upon their own strength; and as to all hypocrites, who, for a time, parade themselves in gay colors. The amount, then, is, that unless God govern us by his Spirit, and keep us in the performance of our duty, so that our hearts may be sound in his statutes, although our shame may be hidden for a time, yea, although all men should praise us, and hold us in admiration, yet we cannot avoid falling, at length, into dishonor and ignominy.

Let my heart be sound - Hebrew, "Be perfect." See the notes at Job 1:1. The Septuagint here is "immaculate," ἄμωμος amōmos. So the Latin Vulgate. It is the expression of a desire that the heart might be pure; that there might be no improper attachment for other objects; that there might be no defect of love to God.
That I be not ashamed - See the notes at Psalm 119:6. A man has no occasion to be ashamed of a pure heart; and that which can alone keep us from being ultimately ashamed is sincerity, uprightness, and purity in the service of God.

Let my heart be sound in thy statutes - Let it be perfect - all given up to thee, and all possessed by thee.

Let my heart be found in thy statutes,.... Or "perfect", and sincere: he desires that he might have a sincere regard to the ways and worship, ordinances and commands, of God; that he might have a cordial affection for them, and observe them, not in show and appearance only, but heartily as to the Lord, and in reality and truth, like an Israelite indeed, in whom there is no guile;
that I be not ashamed; before men, conscious of guilt; or before God, at the throne of grace; where a believer sometimes is ashamed to come, not having had that regard to the statutes of the Lord he should have had, and that he might not be ashamed before him at the last day; but have confidence, having the righteousness of Christ imputed to him, and the true grace of God implanted in him; which engaged him to a regard to all his commandments.

Let my . . . be sound--that is, perfect, sincere.
ashamed--disappointed in my hope of salvation.

Sound - That I may love and obey them sincerely, constantly, and universally.