It is narrated from Abu Huraira (may Allah be pleased with him) that he stated: The Messenger of Allah (peace and blessings be upon him) informed the people of the death of Najashi on the very day he passed away. Then he went to the place of prayer with the people and performed the funeral prayer in congregation with four takbirs.
Hadith Referenceمسند الإمام الشافعي / كتاب الجنائز / 596
Hadith Takhrijاخرجه البخاري، الجنائز، باب الرجل ينعى إلى اهل الميت بنفسه (1245) ۔ ومسلم، الجنائز، باب في التكبير على الجنازة (951)۔