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.