Now this psalm is very special. This has been written at the time Nathan the prophet has admonished David and made him see what he really has done. This was probably an epic moment marking the darkest moment in his life, as such the words are really important.
"I was sinful when my mother conceived me."
"Surely you desire integrity in the inner self" - David had got it! He knew the law has an inner layer which he set himself to discover by meditating on it.
"Purify me with hyssop and I will be clean". That is interesting. Hyssop was used at the day of passover. So it refers to being cleaned by blood!
"Save me from the sin of bloodshed" Is it a reference to Uriah?
All around very beautiful.