仁王經疏 2.217

2.217

釋曰：第二、顯其勝用。謂於此地受變易生，名為法身。證法性如所生身故，名為法身。惑諸功德所依止故，稱為法身。放無量光，照諸國土。

Commentary: Second, revealing its superior function. In this bhūmi, one receives change-manifested birth, which is termed the 'dharmakāya'. Because it is a body produced by realizing the dharmatā of tathatā, it is termed the 'dharmakāya'. Or because it is the locus on which all merits rely, it is called the 'dharmakāya'. Emitting immeasurable light, it illuminates all lands.