Abu Dawud Book 30, Hadith Number 4264.
Chapter : There is an expectation of forgiveness after being killed during the period of commotion fitnah.
Narated By Sa’id ibn Zayd : We were with the Prophet (PBUH). He mentioned civil strife (fitnah) and expressed its gravity. We or the people said: Apostle of Allah, if this happens to us it will destroy us. The Apostle of Allah (PBUH) said; No. It is enough for you that you would be killed. Sa’id said: I saw that my brethren were killed.