When one companion protested that the Holy Prophet had not done justice in the matter of distributing the spoils of war, some people wanted to kill him, but the Holy Prophet stopped them and said: "Wait. Such people, on their own, one day will go out of the true faith, then the best of men among you will kill him." And that man was killed by Ali in the battle of Nahrawan that was fought between Imam Ali and the damned Muawiya.
firstly many people esp. ansar were not happy with distribution of spoils but they were later won over by the speech of the prophet and cried so much " that our beards became wet" to quote them.All these people were not bad but were pious upright honest muslims.
secondly this man u mention is probably hurqus b zuhair who was killed with khawarij not muawiyah