What is the ruling on praying the funeral prayer for an absent deceased, and is it prescribed for every absent person?

"Praying over an absent person (Salat al-Gha'ib) is permissible, and this is confirmed by the prayer of the Prophet, peace be upon him, and his companions over the Negus. There is no evidence to suggest that this was exclusive to him, peace be upon him. The most balanced opinions on the matter are: that one should only pray over someone who has not been prayed over, or that one should pray over someone whose death brings benefit to Muslims, such as a scholar, a warrior (mujahid), or a merchant."