Hazrat Amr bin Aas (may Allah be pleased with him) once sent gifts and presents to some people, and he gave the most to Hazrat Ammar bin Yasir (may Allah be pleased with him). Someone asked the reason for this, so Hazrat Amr (may Allah be pleased with him) said: I heard the Prophet (peace and blessings of Allah be upon him) say that a rebellious group will kill Ammar.