大方廣佛華嚴經隨疏演義鈔 33.58

33.58

疏「鏡現染處」下，二通一難。謂有問言：鏡能現染，復能現淨，豈非異耶？如來藏能成生死，復能成涅槃，豈非異耶？故今答云：現染淨處，無異體故。生死涅槃，一性現故。

Regarding the commentary's "Where the mirror manifests defilement" and following: second, resolving the objection regarding unity. That is, someone asks: the mirror is able to manifest defilement and also able to manifest purity, so is it not different? The tathāgatagarbha can accomplish saṃsāra and can also accomplish nirvāṇa, so is it not different? Therefore, it now replies: where it manifests defilement and purity, there is no different essence. Saṃsāra and nirvāṇa are manifestations of a single nature.