Prayer of the absent Deceased

Question :

How do we pray over the absentee deceased person?

Answer :

The prayer over the absent deceased is just like the prayer over the deceased who is present. For this reason, when the Prophet announced the death of An-Najashi, he ordered the people to come out to the designated prayer area and he arranged them in rows. Then he pronounced the Takbir (saying Allahu Akbar') four times, just like the Takbirs over the deceased who is present.
However, should the funeral prayer be prayed over every absent deceased person or not?

In this issue there is a difference among the people of knowledge. Among them there are those who say that prayer should be made over every deceased person who is absent. Some of them even say that it is necessary for the person to pray the funeral prayer every night, and he should intend by it to pray over whoever died from the Muslims on that day, in the east and the west of the earth. Others have said that no one should be prayed over (for the absent deceased) except for the one whom it is known that he was not prayed over. A third group says that the prayer (for the absent deceased) should be prayed for everyone who had some major influence on the Muslims, such as beneficial knowledge or other things. The correct view is that no one should be prayed for (as an absent deceased) except whoever did not have prayer performed for him.

In the time of the Rightly-Guided Caliphs many people died from those who had dominant influences over the Muslims, and the prayer for the absent deceased was not made for any of them. The fundamental principle concerning acts of worship is At-Tawqif (i.e., it is not to be done) until an evidence is established to prove its legality.

Source:
Ash-Shaykh Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 3 Pages 65-66