Musnad Ahmad 286:7

Abu Sa’id, the freed slave of Banu Hashim, narrated to us, saying: Al-Muthanna ibn Sa’id narrated to us, saying: Qatadah narrated to us, from Abu al-Tufayl, from Hudhayfah ibn Asid, that the Messenger of Allah (peace and blessings of Allah be upon him) came one day and said: "Pray for a brother of yours who has died in a land other than yours." They said: "Who is he, O Messenger of Allah?" He said: "Sahmah, the Negus." So they stood up and prayed over him.