淨名經集解關中疏 2.250

2.250

德頂菩薩曰。垢淨為二。見垢實性則無淨相順於我滅相。是為入不二法門　凡夫倒心見不淨。三乘觀身不淨。此為二也。肇曰。淨生於垢。實性無垢淨。何所淨。

The Bodhisattva Guṇacūḍa said, "Defilement and purity constitute duality. When one sees the true nature of defilement, there is no characteristic of purity, conforming to the characteristic of extinction. This is entering the dharma gate of non-duality."
Ordinary people with perverted minds perceive impurity; the three vehicles contemplate the body as impure. This constitutes duality. Sengzhao says, "Purity arises from defilement. In the true nature there is neither defilement nor purity; what, then, is purified?"