This is well proven Hadith among Sunni fellows, Imam Trimdhi graded as Sahih hadith, Bukhari also wrote that the Holy said a rebellious group will kill Ammar, Ammar will invite them towards heaven but the group will invite Ammar bin Yasir towards hell. We know that Ammar bin Yasir rz got kiled fighting against Moawiya’s army. Please see more details in our research work on Nisai that people were proud on the killing of Ammar bin Yasir in front of Muawiya to get price from him. And Muawiya give the wrong interpretation about the killing of Hazrat Ammar.
Abu Hurayra narrated the Holy Prophet said “I give you good news O Ammar, A rebellious group will kill you.”
This is graded as Hassan Sahih