Excerpt from 'The Message':
Ka'b bin Umayr Ghifari was deputed, along with fifteen others, all of whom were proficient missionaries, to proceed to the region of Zat Atlah, situated on the other side of Wadiul Qura' and to invite the people of that place to embrace Islam. They arrived there and performed the duty entrusted to them.
Suddenly they met with severe opposition from those people and all of them were attacked. The missionary party found itself encircled by a large crowd. They defended themselves valiantly and preferred martyrdom to humility. Only one of them, who was wounded and was lying amongst the dead, got up at mid-night and proceeded to Madina. On reaching there he related the entire incident to the Prophet.
The massacre of the missionaries and the execution of so many innocent persons made the Prophet give orders for jihad. An army consisting of three thousand persons was, therefore dispatched to punish the rebels, and those, who obstructed the spread of Islam.
Orders for jihad were given. Three thousand swordsmen gathered in the military station of Madina (Jurf). The Prophet came to the military station personally and addressed the soldiers saying: 'You should go and invite those people again to embrace Islam. If they accept Islam you need not avenge the murder of the envoy, but otherwise you should seek help from Allah and fight against them.Yes, O soldiers of Islam! Perform jihad in the name of Allah! Punish the enemies of Allah and your own enemies, who live in Syria. Don't interfere with the monks and nuns, who spend their time in monasteries, far removed from the tumult of the world. Destroy all satanic elements, with these very swords. Don't kill women, children and old people. Don't cut trees and don't destroy buildings.Yes! O Mujahids! The commander of the army is my cousin Ja'far bin Abu Talib. If he sustains an injury, Zayd bin Harith will bear the standard and direct the army, and if he is killed Abdullah Rawahid will assume the command. And if he too meets an injury, you may choose the chief commander yourselves.'