Hadith on Shahdat of Hazrat Ammar bin Yasir Radiallahu anhoo

Hazrat Ammar bin Yasir(RA) the loyal servent of Rasool ALLAH(SAWW) and Maula-e-Kainaat Hazrat Ali (KAW) was killed by the transgressing tyrannical Army of Muawiyah ibn Abu Sufyan at the Battle of Siffin.
Abu Huraira(RA) narrated that the Messenger of Allah said : “Rejoice Ammar, the transgressing party shall kill you ” Sunan Thirmidhi : Hadith Number 3800 

Allah’s messenger (PBUH) said to Ammar: “A “group of rebels” would kill you.” – Sahih Muslim, English version, v4,Tradition #6968

Umm Salama narrated that Allah’s messenger (may peace be upon him) said: “A band of rebels would kill Ammar.” – Sahih Muslim, English version, v4, chapter MCCV, Tradition #6970