`Abdullah bin `Umar said:"Allah's Messenger (ﷺ) appointed Zaid bin Haritha as the commander of the army during the Ghazwa of Mu'tah and said, "If Zaid is martyred, Ja`far should take over his position, and if Ja`far is martyred, `Abdullah bin Rawaha should take over his position.' " `Abdulla-h bin `Umar further said, "I was present amongst them in that battle and we searched for Ja`far bin Abi Talib and found his body amongst the bodies of the martyred ones, and found over ninety wounds over his body, caused by stabs or shots (of arrows).
أَخْبَرَنَا أَحْمَدُ بْنُ أَبِي بَكْرٍ، حَدَّثَنَا مُغِيرَةُ بْنُ عَبْدِ الرَّحْمَنِ، عَنْ عَبْدِ اللَّهِ بْنِ سَعِيدٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ ـ رضى الله عنهما ـ قَالَ أَمَّرَ رَسُولُ اللَّهِ صلى الله عليه وسلم فِي غَزْوَةِ مُوتَةَ زَيْدَ بْنَ حَارِثَةَ، فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِنْ قُتِلَ زَيْدٌ فَجَعْفَرٌ، وَإِنْ قُتِلَ جَعْفَرٌ فَعَبْدُ اللَّهِ بْنُ رَوَاحَةَ ". قَالَ عَبْدُ اللَّهِ كُنْتُ فِيهِمْ فِي تِلْكَ الْغَزْوَةِ فَالْتَمَسْنَا جَعْفَرَ بْنَ أَبِي طَالِبٍ، فَوَجَدْنَاهُ فِي الْقَتْلَى، وَوَجَدْنَا مَا فِي جَسَدِهِ بِضْعًا وَتِسْعِينَ مِنْ طَعْنَةٍ وَرَمْيَةٍ.
Bukhari
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi) • Hadith 295