अथ चैनं नित्यजातं नित्यं वा मन्यसे मृतम्।
तथापि त्वं महाबाहो नैवं शोचितुमर्हसि।।2.26।।
On the other hand, if you think this One is born continually or dies constantly, even then, O mighty-armed one, you ought not to grieve thus.
So far Bhagvan explained the pointlessness of grief owing to the eternity and immutability of atman. Now He explains that even if you presume atman to be temporal and mutable by following the common belief in society that atman is born with birth of body and it destroys on the death of body, still there is no point for to grieve.
Because whatever has taken birth is certain to die. And further, whatever dies is certain to be born again. These two are the inevitable truths. Thus, the grief on account of death of atman (presuming the temporality thereof) is illogical.
This being so (in next shloka)