金剛般若波羅蜜經註解 1.140

1.140

而善現即知須彌自無分別：「我是山王。」故得為大。報身離著亦復如是，故曰：「佛說非身，是名大身。」

And Subhūti immediately knew that Sumeru itself is without discrimination that 'I am the king of mountains,' and thus it is able to be large. The reward body's freedom from attachment is also like this; hence he said: "The Buddha said that a non-body is named a large body."