大方廣佛華嚴經隨疏演義鈔 33.54

33.54

疏「四真淨虛染鎔融一味」者，以如來藏舉體成生死，如來藏外無生死故。生死即空，是如來藏，離生死外無如來藏故，如波與水一味無差。

Regarding the commentary's "fourth, the true pure and the false defiled interfuse into a single flavor": because the tathāgatagarbha in its entire essence becomes saṃsāra, outside the tathāgatagarbha there is no saṃsāra. Saṃsāra is identical with emptiness, which is the tathāgatagarbha, because apart from saṃsāra there is no tathāgatagarbha, just as waves and water are of a single flavor without distinction.