12:22 "hyssop" - "Purge me with hyssop, and I shall be clean: wash me, and
I shall be whiter than snow." Psalm 51:7. Hyssop
is used to cleanse a house of mold contamination in
Leviticus 14:52.
This is called "leprosy", which is a type of sin.
"None of you are to go out of your house until morning."
This looks forward to the coming judgement on the nations, as
in Isaiah 26:20.