وَكُلُّ إِهَابٍ دُبِغَ فَقَدْ طَهُرَ
Translation: Every hide that has been tanned becomes pure.
Ihab denotes hide discussed under tanning rules. Dibagh is the treatment that removes residual moisture and substances causing decay.
The word kull (“every”) establishes a broad rule, followed by expressly stated exceptions.