瑜伽論記 4.66

4.66

樂住者六十三說：繫心於內不流散故，住能引樂名為樂住。由此菩薩地言：有漏樂者三界所繫，無漏樂者是不繫攝。今依身心俱有四樂，喜樂樂樂安樂捨樂，故四靜慮得樂住名。欲界無後二，無色無初二，故雖樂現前不名為樂住。又喜樂初二禪樂，安樂是第三禪樂，捨樂是第四禪樂。身心樂者簡無色界非樂住所以。

Regarding 'dwelling happily': fascicle sixty-three says: because the mind is bound internally and does not scatter, the dwelling that can induce pleasure is called 'dwelling happily'. Therefore, the Bodhisattvabhūmi says: pleasure with defilements is bound to the three realms; taintless pleasure is subsumed under the unbound. Now, based on both body and mind possessing the four pleasures—the pleasure of joy, the pleasure of pleasure, the pleasure of pliancy, and the pleasure of equanimity—the four dhyānas obtain the name 'dwelling happily'. The desire realm lacks the latter two, and the formless realm lacks the former two; thus, although pleasure is present to them, it is not called 'dwelling happily'. Furthermore, the pleasure of joy is the pleasure of the first and second dhyānas, the pleasure of pliancy is the pleasure of the third dhyāna, and the pleasure of equanimity is the pleasure of the fourth dhyāna. 'Pleasure of body and mind' distinguishes why the formless realm is not a dwelling happily.