大般涅槃經集解 2.79

2.79

案僧亮曰：昔說無常，䨱今常旨，謂之密教也。僧宗曰：顯三乘為方便、一乘是實行，丈六是有為、法身是無為者也。

Sengliang comments: In the past he spoke of impermanence, concealing the present purport of permanence; this is called the 'esoteric teaching'. Sengzong says: Revealing that the three vehicles are skillful means and the One Vehicle is the true practice, that the sixteen-foot body is saṃskṛta and the dharmakāya is asaṃskṛta.