Wa `alaykum as-salam wa rahamatullah wa barakatuh

 

Allah stated in the Quran, “It is not (proper) for the Prophet and those who believe to ask Allah’s forgiveness for the disbelievers, even though they be of kin, after it has become clear to them that they are the dwellers of the Fire [because they died in a state of disbelief]” (At-tawbah 9:113)

On commenting on this verse, Imam Al-Qurtubi; an exegete of the Quran said, “Allah has not given permission to the believers to pray for forgiveness for the polytheists.” (Al-Qurtubi, al-Jaami’ 3:173).

 

Similarly, the Prophet has been reported as saying, “I asked my Lord for permission to pray for forgiveness for my mother, and He did not permit me. I asked Him for permission to visit her grave, and He granted me permission.” (Muslim)

Therefore, it is not permissible to pray for your grandfather who died in the state of disbelief.