This is a blending together of the prayers found in Psalm 139 and Psalm 51. In these, David asks God to search him, know him, test his heart, have mercy on him, and pleads with God to purify him. David, in pursuit of greater intimacy with God, knows that he will more fully experience God’s presence when his heart and motives are submitted to God.

Search me, O God, and know my heart 
Try me and know my thoughts 
See if there be any grievous way in me 
And lead me in the way everlasting 
You know when I sit down and when I rise up 
You discern the layers of my motives  
You see my blindspots that I cannot 
You are acquainted with all my ways 
Even before a word is on my tongue 
Behold, O Lord, you know it altogether 
And you love me still 
Have mercy on me, O God, according to your loyal love According to your abundant mercy, blot out my transgressions Wash me from my iniquity, and cleanse me from my sin Wash me, and I shall be whiter than snow 
Purify me from within 
Let me hear the gladness of forgiveness 
Let the bones that you have broken rejoice 
Restore unto me the joy of your salvation 
And uphold me with a willing spirit 
Deliver me from the prison of guilt, O God 
And my tongue will sing aloud of your righteousness Open my lips, and my mouth will declare your praise 
Search me, O God, and know my heart 
Try me and know my thoughts 
See if there be any grievous way in me 
And lead me in the way everlasting