金光明經文句記 3.48

3.48

初、以偈對德。碎地為塵尚無淨相，豈存於穢？故對淨德，喻於理淨淨於淨穢也。

First, matching the verses to the virtues. Pulverizing the earth into dust does not even leave the mark of purity, so how could defilement remain? Therefore it is matched to the virtue of purity, symbolizing that the purity of principle purifies both purity and defilement.