Messenger of Allah ﷺ informed (the people) about the death of An-Najashi on the very day he died. He went towards the Musalla (praying place) and the people stood behind him in rows. He said four Takbirs (i.e. offered the Funeral prayer).  

أَنَّ رَسُولَ اللَّهِ ﷺ نَعَى النَّجَاشِيَّ فِي الْيَوْمِ الَّذِي مَاتَ فِيهِ خَرَجَ إِلَى الْمُصَلَّى فَصَفَّ بِهِمْ وَكَبَّرَ أَرْبَعًا  

The Prophet ﷺ said, "Zaid took over the flag and was martyred. Then it was taken by Jafar who was martyred as well. Then ʿAbdullah bin Rawaha took the flag but he too was martyred and at that time the eyes of Messenger of Allah ﷺ were full of tears. Then Khalid bin Al-Walid took the flag without being nominated as a chief (before hand) and was blessed with victory."  

قَالَ النَّبِيُّ ﷺ أَخَذَ الرَّايَةَ زَيْدٌ فَأُصِيبَ ثُمَّ أَخَذَهَا جَعْفَرٌ فَأُصِيبَ ثُمَّ أَخَذَهَا عَبْدُ اللَّهِ بْنُ رَوَاحَةَ فَأُصِيبَ وَإِنَّ عَيْنَىْ رَسُولِ اللَّهِ ﷺ لَتَذْرِفَانِ ثُمَّ أَخَذَهَا خَالِدُ بْنُ الْوَلِيدِ مِنْ غَيْرِ إِمْرَةٍ فَفُتِحَ لَهُ