Abu Dawud Book 30, Hadith Number 4258.

Chapter : Gravity of the sin of killing a beleiver.

Narated By Khalid b. Dihqan : I asked Yahya b. Yahya al-Ghassani about the word i’tabata bi qatalihi spoken by him (as mentioned in the previous tradition). He said: It means those people who fight during the period of commotion (fitnah), and one of them kills (the other people) presuming that he is on the right, so he does not beg the pardon of Allah for that (sin).

Abu Dawud said: And he said: The word fa’tabata means “he shed blood profusely.”