Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: The Prophet (peace and blessings be upon him) dispatched an expedition to Mu'tah. He appointed Sayyiduna Zayd (may Allah be pleased with him) as their commander and said: "If Zayd is martyred, then Ja'far will be commander; if Ja'far is martyred, then Abdullah bin Rawahah will be commander."
Ahmad recorded it as part of a long hadith. Its chain contains a narrator, al-Hajjaj bin Artah, who is a mudallis. The remaining narrators of this report are the narrators of the Sahih.