金剛經纂要刊定記 7.57

7.57

亦是約喻法說者。若化是實，亦不用佛說，只為是虛餘人不知，故佛說矣。

"It is also spoken in terms of metaphor and Dharma": If the transformation were real, it would not require the Buddha to speak of it; it is only because it is unreal and other people do not know it that the Buddha speaks of it.