瑜伽師地論略纂 1.93

1.93

災頂之中，初禪橫量大小，猶如欲界，既同一火，千个初禪方等於一二禪之量，二禪火災不及，故說二禪為火災頂。千个二禪方等於一三禪之量，二禪已下既同水災，水災不能壞第三禪，故說三禪為水災頂。千个三禪方等於一四禪之量，三禪已下同一風災，風既不壞四禪，故說四禪為風災頂。

Regarding the summits of the disasters: the horizontal extent of the first dhyāna is equal to that of the desire realm; since they share the same fire, only one thousand first dhyānas equal the extent of a single second dhyāna. The fire disaster does not reach the second dhyāna, hence the second dhyāna is said to be the summit of the disaster of fire. One thousand second dhyānas equal the extent of a single third dhyāna; since the second dhyāna and below share the disaster of water, and the water disaster cannot destroy the third dhyāna, the third dhyāna is said to be the summit of the disaster of water. One thousand third dhyānas equal the extent of a single fourth dhyāna; since the third dhyāna and below share the same disaster of wind, and wind does not destroy the fourth dhyāna, the fourth dhyāna is said to be the summit of the disaster of wind.