Musnad Ahmad 658:100

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Abu Ishaq, who said: I heard Al-Bara' ibn 'Azib saying: When the Messenger of Allah (peace and blessings of Allah be upon him) made a peace treaty with the people of Al-Hudaybiyah, Ali (may Allah be pleased with him) wrote a document between them. He said: So he wrote, "Muhammad, the Messenger of Allah." The polytheists said: "Do not write 'Muhammad, the Messenger of Allah,' for if you were the Messenger of Allah, we would not have fought you." He said: So he (the Prophet) said to Ali: "Erase it." He said: He replied, "I am not the one who will erase it." So the Messenger of Allah (peace and blessings of Allah be upon him) erased it with his own hand. He said: And he made peace with them on the condition that he and his companions would enter for three days, and they would not enter except with the *jalban* of weapons. I asked him: "What is the *jalban* of weapons?" He said: "The scabbard with what is in it."