O Lord, you have searched me and known me!
This has profound implications for prayer. My own heart is deceitful (Jeremiah 17:9) and my prayers inarticulate (Romans 8:26), yet God knows exactly what I need before I even ask (Matthew 6:8). He knows if there is secret sin in my heart (Psalm 90:8), conversely, He also knows how much I love Him (John 21:17).
If I stray from God, His knowledge of my every thought and deed is terrifying, if I draw near to Him it is a great comfort. Either way, His total knowledge of me is essential because this is what keeps me alive (Matthew 10:29-30).