[30:12] 1 tn The verb רָחַץ (rakhats) means “to wash; to wash off; to wash away; to bathe.” It is used of physical washing, ceremonial washings, and hence figuratively of removing sin and guilt through confession (e.g., Isa 1:16). Here the form is the Pual perfect (unless it is a rare old Qal passive, since there is no Piel and no apparent change of meaning from the Qal).
[30:12] sn The point of the verse is that there are people who observe outer ritual and think they are pure (טָהוֹר [tahor] is the Levitical standard for entrance into the sanctuary), but who pay no attention to inner cleansing (e.g., Matt 23:27).
[30:12] 2 sn Filthiness often refers to physical uncleanness, but here it refers to moral defilement. Zech 3:3-4 uses it metaphorically as well for the sin of the nation (e.g., Isa 36:12).