जातस्य हि ध्रुवो मृत्युर्ध्रुवं जन्म मृतस्य च।
तस्मादपरिहार्येऽर्थे न त्वं शोचितुमर्हसि।।2.27।।
For death of anyone born is certain, and of the dead (re-) birth is a certainly. Therefore you ought not to grieve over an inevitable fact.
Bhagvan explained in the previous verse that anything which takes birth is certain to get destroyed and the destroyed entity is certain to be born again.
In this verse, He explains that therefore death is an inevitable certain reality for one who is born and similarly birth is also an inevitable reality for one who dies. Thus the sequence of birth and death is unavoidable and is just a routine affair. In view of this, the grief on account of inevitable and unavoidable is pointless.
Now Bhagvan explains the pointlessness of grief presuming the living beings to be mere assemblage of senses and organs (in next shloka).