成唯識論述記 7.140

7.140

述曰：二唯欲界，所以者何？以餘二界妙故無有。妙者勝義，若身有疲極憂根等故，方有眠、悔，彼無此等，故名為妙。其後尋、伺及初定者，以餘上地皆是靜故，尋、伺囂繁非靜，非靜故，靜處無有，或靜及妙皆通二種。第二子門上下相起。

The Commentary states: The two belong exclusively to the desire realm. Why? Because the remaining two realms are exquisite, they do not exist [there]. 'Exquisite' means superior. Only when the body has extreme fatigue, the faculty of sorrow, and so forth do sleep and regret exist; those [higher realms] lack these, and are therefore called exquisite. As for the subsequent investigation and analysis and the first dhyāna, because the remaining higher stages are all tranquil, whereas investigation and analysis are noisy and complex, not tranquil, and being not tranquil they do not exist in tranquil places; or else tranquility and exquisiteness both extend to the two. The second sub-door is mutual arising between lower and higher.