It is narrated from Sayyiduna Hudhaifah bin Asid that one day the Prophet (peace and blessings be upon him) informed us of the death of Najashi and said: "Offer the funeral prayer for your brother who did not die in your region." The companions asked: "O Messenger of Allah! Who is he?" The Prophet (peace and blessings be upon him) said: "Ashamah Najashi."
Hadith Referenceمسند احمد / مسند المدنيين رضي الله عنهم اجمعين / 16147