A person may be undergoing punishment in his grave, even if it is a light punishment. So if you ask Allah to grant him safety, he will be spared. Then you extend the greeting to all the occupants of the graves.
“Peace be upon you, abode of a believing people. And, if Allah wills, we shall surely join you …”
His statement, “Peace be upon you,” uses the second-person plural suffix. Does this suffix indicate that they can hear, since one addresses only someone who can hear, unless there is clear evidence that the one addressed cannot hear? I say, “unless there is clear evidence,” so that no one may raise against us the example of Umar’s statement to the Black Stone: “I know that you are a stone that can neither benefit nor harm. Had I not seen the Prophet ﷺ kiss you, I would not have kissed you.” (1) Here, he addressed it even though it was a stone,