大乘起信論廣釋卷第三．四．五 4.122

4.122

論。唯一真心至虛空相故　釋曰。此顯法身非有。遍常唯一等者辨法同喻。以佛法身唯一真心。由此法身無所不遍。無不遍故是顯如來智性廣大究竟之義。如虛空義故喻虛空。故新論云　此是如來自性廣大如虛空義。非如虛空相故者。簡法異喻。非謂如彼是常。是有妄虛空相故。新論云。非謂如空是常遍有。

[Treatise:] There is only the one true mind, [... the mark of empty space].
[Commentary:] This reveals that the dharmakāya is not an existing, omnipresent permanence. 'Only the one, and so forth': analyzing the dharma as conforming to the metaphor. Because the dharmakāya of the Buddha is only the one true mind, by virtue of this the dharmakāya is all-pervading. Being all-pervading reveals the meaning of the vastness and ultimacy of the Tathāgata's nature of wisdom; because it has the meaning of empty space, it is compared to empty space. Thus the new translation says: "This has the meaning of the Tathāgata's intrinsic nature being vast like empty space." 'Because it is not like the mark of empty space': distinguishing the dharma from a disparate metaphor. It does not mean being permanent and existent like that false mark of empty space. Hence the new translation says: "It does not mean being permanent and omnipresently existing like space."