Here is, 1. David's prayer for sincerity, that his heart might be brought to God's statutes, and that it might be sound in them, not rotten and deceitful, that he might not rest in the form of godliness, but be acquainted with the subject to the power of it, - that he might be hearty and constant in religion, and that his soul might be in health. 2. His dread of the consequences of hypocrisy: That I be not ashamed. Shame is the portion of hypocrites, either here, if it be repented of, or hereafter, if it be not: "Let my heart be sound, that I fall not into scandalous sin, that I fall not quite off from the ways of God, and so shame myself. Let my heart be sound, that I may come boldly to the throne of grace, and may lift up my face without spot at the great day."

How many are the days of thy servant?.... If this is to be understood of the days of his life, they were very few, as the days of every man be; and if of his days of joy and comfort, peace and prosperity, they were fewer still; but if of days of adversity and affliction, which seems to be the sense, they were many indeed;

when wilt thou execute judgment on them that persecute me? good men have their persecutors; there is a judgment that will be executed on them, if not here, yet hereafter; it is a righteous thing with God to do it; it is often deferred when the saints, through zeal for the glory of God, and the honour of his justice, as well as for their own deliverance and comfort, are at times somewhat impatient for it, and earnestly solicit it, as the psalmist here; see Rev 6:9.