瑜伽論記 6.433

6.433

遠公言：準涅槃經，鳥獸細毛名毳，行者若無糞衣可得，取此為衣。

Venerable Yuan says: according to the *Nirvāṇa Sūtra*, the fine down of birds and beasts is called *cui*; if a practitioner cannot obtain rag robes, he takes this for his robe.