金剛經纂要刊定記 3.178

3.178

以下標云善護念等。如來者，真化不同。真佛名如來者，迷時背覺合塵名如去，悟了背塵合覺名如來，如即真如，來去即隨緣也。化佛名如來者，從真如起，來成正覺而化眾生。今當後者，故云從如而來。

Below, it points out "good mindfulness and protection" and so forth. Regarding "Tathāgata," true and transformed [Buddhas] are not the same. When a true Buddha is called Tathāgata: when deluded, turning away from awakening and conforming to the dusts is called "tathā-gata" (gone to suchness); when awakened, turning away from the dusts and conforming to awakening is called "tathā-āgata" (come from suchness). "Tathā" is tathatā, and "coming and going" means according with conditions. When a transformed Buddha is called Tathāgata: arising from tathatā, coming to achieve right awakening and transform sentient beings. The present case concerns the latter; hence it says "coming from suchness."