瑜伽論記 7.415

7.415

尋思共相者，爾時行者知內自身淨色未壞，然同外身已變壞色變壞法性不淨相似，名為共相。

Regarding 'investigating common characteristics': at that time, the practitioner knows that the pure form of their own internal body has not yet decayed, yet it resembles the decayed form of an external body in the dharmatā of decay and in impurity; this is called a common characteristic.