瑜伽論記 1.464

1.464

展轉熾盛，極至梵世者，欲色界色麁細類殊，不可下火而燒上器，大勢相接，漸壞世間，故言展轉實別火壞。

As for 'gradually flaring up, reaching up to the Brahmā world,' form in the desire and form realms differs in coarseness and fineness, so a lower fire cannot burn an upper receptacle; their great power comes into contact, gradually destroying the world, so it is said to be "gradual," but in fact separate fires destroy them.