Read Psalms 51:7  David felt really bad about his sin.  Sometimes we feel bad about our sin only because we were caught.  David was caught in his sin and Nathan the prophet told him so.  But David was truly sorry for his sin.  In the Old Testament, the Jews had to offer a lamb as the sacrifice for their sins.  The person would bring the lamb to the Temple to the priest.  The person would then lay his hands upon the head of the lamb and then the priest would kill the lamb.  That is a picture of our sins because the lamb did nothing wrong to deserve to die; the lamb died as a sacrifice for the person's sins.  Then the priest would take some of the lamb's blood in a bowl and dip a small branch from the hyssop bush into the blood and sprinkle the blood before the Lord.  That's why in our verse David asked the Lord to purge him with hyssop.  And then David said that when the Lord cleaned away his sin, he would be as clean as snow.  Isn't it great to know that you are forgiven of your sins.  When you are forgiven, you feel clean inside.  That is because God has cleaned your sins away and you are back to getting along with God as your best friend.  Tonight, let's pray and thank the Lord for cleaning our heart and for taking away our sins!