大般涅槃經義記 7.46

7.46

後句云何？若未生時全無生性，如來可說不生不生；未生之時已有生性，云何佛說不生不生？難意如是。然有為法先未生時，雖無生事已有生性，故今反舉。「未生無生，何故不說虛空為生」以理難破。若有為法本無生性後得生者，虛空本來亦無生性，何故不生？虛空不生，可先無生；有為可生，明本有生。本有生故，非不生不生。

What is the latter line? If at the time when it has not yet arisen it entirely lacked the nature of arising, the Tathāgata could speak of "not arising when not [yet] arisen"; but at the time when it has not yet arisen it already had the nature of arising, so why does the Buddha speak of "not arising when not [yet] arisen"? Such is the intention of the objection. However, when conditioned dharmas have not yet arisen previously, although they lack the occurrence of arising, they already have the nature of arising; therefore he now raises the contrary: "If when not [yet] arisen there is no arising, why is space not said to arise?" refuting it through reason: if conditioned dharmas fundamentally lacked the nature of arising and only later came to arise, space fundamentally also lacks the nature of arising, so why does it not arise? Since space does not arise, it may be that previously there was no arising; but conditioned [dharmas] can arise, which clearly shows that fundamentally there is arising. Because fundamentally there is arising, it is not "not arising when not [yet] arisen."