I asked Yahya b. Yahya al-Ghassani about the word i'tabata bi qatlihi 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 in the right, so he does not beg pardon of Allah of that (sin). Abu Dawud said: And he said: The word fa'tabata means "he shed blood profusely"
عَنْ قَوْلِهِ اعْتَبَطَ بِقَتْلِهِ قَالَ الَّذِينَ يُقَاتِلُونَ فِي الْفِتْنَةِ فَيَقْتُلُ أَحَدُهُمْ فَيَرَى أَنَّهُ عَلَى هُدًى لاَ يَسْتَغْفِرُ اللَّهَ يَعْنِي مِنْ ذَلِكَ