四分律行事鈔資持記 3.173

3.173

畜意中。雖重謂貴重也。準知拾糞掃者，乃通眾物，不獨在衣；但人所棄，不必麁弊。

In the intention of keeping them: "although heavy" means precious and heavy. Based on this, one knows that gathering dust-heap rags applies generally to various articles, not solely to robes; as long as they are discarded by people, they need not be coarse and worn-out.