When is it prescribed to offer the funeral prayer in absentia?

The most correct scholarly view is that offering the funeral prayer in absentia is not prescribed except when the funeral prayer has not been offered for the deceased, such as when a person dies in a kaafir land and no one offers the funeral prayer for him, because it is obligatory to offer the funeral prayer. As for those for whom the funeral prayer has been offered, the correct view is that it is not prescribed to offer the funeral prayer for them, i.e., in absentia, because that was not narrated in the Sunnah except in the case of the Negus (the ruler of Abyssinia), because the funeral prayer was not offered for the Negus in his own country. Hence the Prophet (peace and blessings of Allaah be upon him) offered the funeral prayer for him in Madeenah. Other great men and leaders died but there is no report that he (peace and blessings of Allaah be upon him) offered the funeral prayer for them. 

Some of the scholars said: Whoever has benefited Islam by means of his wealth or knowledge, the funeral prayer may be offered for him in absentia … but if that is not the case then the funeral prayer should not be offered. Some scholars said that the funeral prayer may be offered in absentia in all cases, but this is the weakest of the scholarly views.