What did the Prophet Muhammad (saw) order in the battle of Mu'tah regarding the command of the army if Zaid and Ja'far (peace be upon them both) were martyred?
 Narrated Nafi`:                     Ibn `Umar informed me that on the day (of Mu'tah) he stood beside Ja`far who was dead (i.e. killed in the battle), and he counted fifty wounds in his body, caused by stabs or strokes, and none of those wounds was in his back. `Abdullah bin `Umar said, "Allah's Apostle 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).