John Calvin Commentary Psalms 139:23

"Search me, O God, and know my heart: Try me, and know my thoughts;" — Psalms 139:23 (ASV)

Search me, O God! He insists on this as being the only reason he opposed the despisers of God: that he himself was a genuine worshipper of God and desired others to have the same character. It indicates remarkable confidence for him to submit himself so boldly to the judgment of God.

But, being fully conscious of sincerity in his religion, it was not without due consideration that he placed himself so confidently before God's bar. Nor should we think that he claims to be free from all sin, for he groaned under the felt burden of his transgressions. The saints, in all that they say of their integrity, still depend only on free grace.

Yet, persuaded as they are that their godliness is approved before God, despite their falls and infirmities, we should not wonder that they feel free to draw a distinction between themselves and the wicked.

While he denies that his heart was double or insincere, he does not profess to be exempt from all sin, but only that he was not devoted to wickedness. For עצב, otseb, does not mean any sin at all, but grief, trouble, or depravity — and sometimes metaphorically, an idol.

But the last of these meanings will not apply here, for David asserts his freedom not from superstition only, but from unrighteousness. As it is said elsewhere (Isaiah 59:7), that in the ways of such men there is trouble and destruction, because they achieve everything by violence and wickedness.

Others think the allusion is to a bad conscience, which afflicts the wicked with inward torments, but this is a forced interpretation. Whatever sense we attach to the word, David’s meaning simply is that, though he was a man subject to sin, he was not devotedly bent on practicing it.