The Hearing power of the Deceased
Some persons believe that the deceased do not have the power to hear. The Aqeeda of the Ahle Sunnah Wal Jama’at is that the dead have the power of hearing.
When the Holy Prophet (sallal laahu alaihi wasallam) passed by a graveyard he used to say: “O Dwellers of the Grave! Peace be upon you! May Allah forgive you and us. You have come before us and we are to come after you.” (Jaame Tirmizi; Shara Sudoor fi Ahwaali Mouta wal Quboor) The words “Ya Ahle Quboor” make it obvious that the dwellers of the grave can hear.
Sayyiduna Anas (radi Allahu anhu) reports that the Holy Prophet Muhammad (sallal laahu alaihi wasallam) said: “Verily, when a person is placed in the grave and when his friends return, then he hears the sound of their footsteps (shoes)”. (Mishkaat Shareef; Sahih Bukhari)
When the nations of Thamud were destroyed after the punishment of Allah Ta’ala descended upon them, Sayyiduna Saleh (alaihis salaam) spoke to them. The Holy Quran confirms says: “Hence he turned his face away and said, ‘O my people! Undoubtedly, I did deliver to you the Messages of my Lord, and wished you good, but you do not approve the well wishers’.” (Part 8, Ruku 17) In this verse of the Holy Quran, the Nabi of Allah Ta’ala addresses the dead by using the term “Ya” which is proof enough that the dead can hear.
When the Kufaar were defeated in the Battle of Badr and were thrown into a well, the Holy Prophet (sallal laahu alaihi wasallam) stood beside the well and spoke to the dead. He said, “O certain person, son of certain person. O certain person, son of certain person. Does this make you sad that you should have followed Allah and his Rasool (sallal laahu alaihi wasallam)?” He then said, “Verily I have found the promise of my Creator to be true. Did you find the promise of your Creator to be true? ” When Sayyiduna Umar Farouk (radi Allahu anhu) heard this, he said, “Ya Rasoolallah! (sallal laahu alaihi wasallam). Are you conversing which such bodies in which there are no souls?” The Holy Prophet (sallal laahu alaihi wasallam) said, “A Oath on that Being in Whose control is the life of Muhammad (sallal laahu alaihi wasallam)! You cannot hear better than them, that which I am saying.” (Mishkaat Shareef; Sahih Bukhari Shareef; Sahih Muslim Shareef)
Therefore, when one visits the graveyard, it is permissible to greet the inmates of the Qabar as they can hear and they even respond to our greetings.