大般涅槃經義記 7.307

7.307

上來辯相，下釋名義。「何故名為金剛三昧」問以起發，「如金剛」下三義釋之：一不定義，如世金剛，若置日中，色則不定，此定如是於大眾中現種種身；二最勝義，如世金剛體精勝故無能平價，此定如是無能平量；三勢力義，如世金剛除貧去毒，有大勢力，此定如是，若有得者，離煩惱苦、諸魔邪毒。「是名」總結。

The above explains the characteristics; below it explains the meaning of the name. 'Why is it called the Vajra Samādhi?' raises a question to introduce it; from 'Like a vajra...' onward, it is explained through three meanings: First is the meaning of non-fixedness—like a worldly vajra, if placed in the sun, its colour is not fixed; this samādhi is likewise, manifesting various bodies among the great assembly. Second is the meaning of supreme excellence—like a worldly vajra, because its substance is pure and superior, nothing can equal its value; this samādhi is likewise, nothing can measure it. Third is the meaning of power—like a worldly vajra, it removes poverty and eliminates poison, possessing great power; this samādhi is likewise, if anyone attains it, they are freed from the suffering of afflictions and the evil poisons of the māras. 'This is called...' is the general conclusion.