The Idea of the Trench

In the fifth year of the Hijrah, the Quraysh and their allies marched on Madinah with a very large force. The Muslims were far fewer, and the city was open on the north.

Salman, who knew Persian methods of defence, suggested digging a trench across the open side. The Prophet ﷺ accepted, and the Muslims dug it, in cold and hunger, the Prophet ﷺ digging beside them. The enemy had never seen such a thing in Arabia; they were stopped at its edge for weeks until Allah sent a storm that broke their camp.

When the Muhajirun and the Ansar each claimed Salman as one of their own, the Prophet ﷺ is reported to have said, "Salman is from us, the people of the house." This is widely quoted.