Dead people don't exist

Nor at any time verily was I not, nor thou, nor these princes of men, nor verily shall we ever cease to be, hereafter. 2:12

So don't grieve for them.

The wise grieve neither for the living nor for the dead. 2:11

Thou shouldst not grieve. 2:25

Certain is death for the born, and certain is birth for the dead; therefore over the inevitable thou shouldst not grieve. 2:27

The self that exists in everyone's body can never be killed. So don't grieve for any creature. 2:30