妙法蓮華經玄義 4.70

4.70

無想天有，用如虛空三昧者，外道非空，妄計涅槃，謂果報非空，三諦皆非虛無。修諸空淨之行，自成、成他（云云）。

As for the existence of the Heaven of Non-conception being destroyed by the like-empty-space samādhi: non-Buddhists take non-emptiness to falsely reckon nirvāṇa, stating that the retribution is non-empty, and that the three truths are not empty nothingness. Cultivating practices of emptiness and purity, he personally perfects and perfects for others, and so on.