This is one of my favorite Paslm! I love how David descrid how great and big our God is and yet, that He knows everything about each and every one of is children, that He is always with us, that no one can hide from Him. Then David express to God his hatred for tghe wicked and asks God to seach him, to test him, to make sure he doesn't fall in to the category of people he himself despise!

I make this my prayer, it is not a safe one and it might hurt, but I'll take the chance and let God transform me!

Search me, O God, and know my heart;
test me and know my anxious thoughts.
Point out anything in me that offends you,
and lead me along the path of everlasting life.

Psalm 139:1-21 and Psalm 139:23-24