David wants purification (Ps 51:6-51:9)

“You desire truth in the inward being.

Therefore teach me wisdom

In my secret heart.

Purge me with hyssop!

Then I shall be clean.

Wash me!

Then I shall be whiter than snow.

Let me hear joy and gladness!

Let the bones that you have crushed rejoice!

Hide your face from my sins!

Blot out all my iniquities!”

David wanted to be purified. He wanted wisdom in his heart. He wanted to be purged or purified with some ritual that involved a hyssop, a ceremonial plant that was used to sprinkle water in a cleansing ritual. The hyssop was used in cleansing lepers in Leviticus, chapter 14. This cleansing hyssop was more explicit in Numbers, chapter 19, as the main tool used in sprinkling water to ritually clean things. He wanted to be clean, whiter than snow. There was a mention of some crushed bones. He wanted to be joyful, not with broken bones. He wanted his sins hidden and blotted out. He wanted a clean slate.