Al-Waqidi (may Allah have mercy on him) said that Muhammad bin Maslamah (may Allah be pleased with him) struck Marhab on the shins and cut both of them off. Marhab said: "O Muhammad, finish me off quickly." Muhammad (may Allah be pleased with him) said: "Taste death as my brother Mahmud tasted it," and he left him and went on. Sayyiduna Ali (may Allah be pleased with him) passed by him, struck off his head and took his belongings. The two of them (Muhammad and Ali, may Allah be pleased with them both) brought their dispute over the salab (the slain man's gear) to the Messenger of Allah (peace and blessings be upon him). Muhammad (may Allah be pleased with him) said: "O Messenger of Allah, by Allah, I only cut off his legs and left him so that he would taste death, and I was certainly able to finish him off." Sayyiduna Ali (may Allah be pleased with him) said: "He has spoken the truth; I only struck off his head after he had cut off his legs." So the Messenger of Allah (peace and blessings be upon him) gave Marhab's sword, coat of mail and helmet to Muhammad bin Maslamah (may Allah be pleased with him). That sword was with the family of Muhammad bin Maslamah (may Allah be pleased with him), and something was written on it, but no one knew what it said until a Jew from Tayma' read it. It said: "This is the sword of Marhab; whoever tastes it will perish."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12779