俱舍論疏 29.51

29.51

論「次四解脫至性微劣故」，出次四無色解脫體。於四無色唯取定善，非散善及染。

The passage of the treatise starting with "The next four liberations... until: because their nature is weak and inferior" sets forth the essence of the next four formless liberations. In the four formless realms, only absorbed wholesome [states] are taken, not unabsorbed wholesome nor defiled [states].