There is a generation that are pure in their own eyes, and yet is not washed from their filthiness.
– Proverbs 30:12
[V]erses 12-14 of this group, beginning with verse 11, all use metaphoric references—eyes, eyelids, teeth, and jaw. The generation, or group, in this saying are guilty of self-justifying pride (Proverbs 20:9; 21:2). The word for pure means clean and can refer to cleanness in a physical, moral, or ceremonial sense. The word for filthiness is a strong word that can refer to excrement (2 Kings 18:27). The saying depends on a contrasting parallel of people proclaiming their own cleanness while they are covered with dung. The imagery is shocking and even disgusting, but it reflects the true view God has of our own cleanness (Proverbs 16:2; Isaiah 64:6).