Albert Barnes 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 - The word “search” here is the same as in (Psalms 139:1). See the notes at that verse. The psalmist had stated the fact that it is a characteristic of God that he “does” search the heart; and he here prays that God “would” exercise that power in relation to himself; that as God could know all that there is within the heart, he would examine him with the closest scrutiny, so that he might be under no delusion or self-deception; that he might not indulge in any false hopes; that he might not cherish any improper feelings or desires. The prayer denotes great “sincerity” on the part of the psalmist.

It also indicates self-distrust. It is an expression of what all must feel who have any just views of themselves—that the heart is very corrupt; that we are liable to deceive ourselves; and that the most thorough search “should” be made so that we are “not” deceived and lost.

And know my heart - Know or see all that is within it.

Try me - As metal is tried or proved when it is put to a “test” to learn what it is. The trial here is that which would result from the divine inspection of his heart.

And know my thoughts - See what they are. The word rendered “thoughts” occurs in only one other place (Psalms 94:19). The idea is, Search me thoroughly; examine not merely my outward conduct, but what I think about; what my purposes are; what passes through my mind; what occupies my imagination and my memory; what secures my affections and controls my will. He must be a very sincere man who prays that God will search his thoughts, for there are few who would be willing that their fellow men, even their best friends, should know all that they are thinking about.