大方廣佛華嚴經隨疏演義鈔 1.19

1.19

疏「混虛空為體性」者，三有一句，明體玄也。然有二義：一約世尊身上自具十身，即法身也。以法性身為法身故，故下經云「性空即是佛，不可得思量。」又云「佛以法為身，清淨如虛空。」二者約外虛空，以融三世間而為佛身，則外虛空是虛空身故，故云「混虛空為體，性混融無礙」故。

The Commentary states: "Merging with empty space as the essential nature": third, there is one clause, clarifying the profundity of the essence. There are two meanings: first, in terms of the World-Honoured One's body inherently possessing the ten bodies, this is precisely the dharmakāya. Because the dharmatā body is the dharmakāya, the sūtra below states: "Nature-emptiness is precisely the Buddha, beyond reckoning." It also says: "The Buddha takes the Dharma as body, pure as empty space." Second, in terms of external empty space, by fusing the three worlds into the Buddha's body, external empty space is the space body; hence it says "merging with empty space as the essence," because its nature is fused and unimpeded.