俱舍論疏 28.104

28.104

論「第四靜慮至足前為十一」，增非苦樂者，雖捨受即是前受，五受明義，增前非苦樂也。若合四地受為一，即九法為支體也。

On the treatise passage: "In the fourth dhyāna [...] bringing the previous [total] to eleven": as for adding neither-painful-nor-pleasurable [feeling], although neutral feeling is just the previous feeling, when the meaning is explained in terms of the five feelings, it is added to the previous ones as neither-painful-nor-pleasurable [feeling]. If the feelings of the four levels are combined as one, then nine dharmas constitute the entities of the factors.