The Noble Prophet (s.a.w) had started out for a battle and on the way ordered his army to halt. In order to relieve himself, he distanced himself from his forces and headed towards a secluded location. In the meantime, it began to rain and it rained so hard that water began to flood as a result of which, the Noble Prophet (s.a.w) was cut off from his army.
Having witnessed the change in weather, he (s.a.w) sat beneath a tree when Huwairith Ibn al-Harith happened to see him. Speaking to his companions, he said: “This man is Muhammad and he has become isolated from his forces. May Allah kill me if I do not kill him!”
He unsheathed his sword and rushed at him (s.a.w) saying: “Who is it that can deliver you from me?” The Noble Prophet (s.a.w) said: “Allah” and then prayed softly: “O’ Lord! Deliver me from the evils of Huwairith in any manner as you please.”
Just as Huwairith was about to inflict his blow an angel struck him on his shoulder as a result of which he collapsed onto the ground and the sword fell from his grasp. The Noble Prophet (s.a.w) picked it up and said to him: “Who is it that can save you from me?” He said: “No one.” The Noble Prophet (s.a.w) advised: “Accept Islam and I shall hand your sword back to you!” He said: “I shall not accept Islam but I shall pledge that neither shall I fight you and your followers, nor help anyone against you.”
The Noble Prophet (s.a.w) returned his sword to him whereupon, Huwairith said: “I swear that you are better than me.”( Dastan-ha Wa Pand-ha, vol. 2, pg. 67; The commentary of Abul Futuh )