Ibn 'Umar (RAA) narrated that The Messenger of Allah (ﷺ) said:

“Three types of people are most hated by Allah, the Almighty: whoever kills another in the Sacred area of Haram (Sanctuary), whoever kills anyone other than the one who killed him or whoever kills anyone in revenge as in times of Jahiliyah (pre-Islamic times).” Related by Ibn Hibban.

وَعَنْ اِبْنِ عَمْرٍو [1]‏ رَضِيَ اَللَّهُ عَنْهُمَا, عَنْ اَلنَّبِيِّ ‏- صلى الله عليه وسلم ‏-قَالَ: { إِنَّ أَعْتَى اَلنَّاسِ عَلَى اَللَّهِ ثَلَاثَةٌ: مَنْ قَتَلَ فِي حَرَمَ اَللَّهِ, أَوْ قَتَلَ غَيْرَ قَاتِلِهِ, أَوْ قَتَلَ لِذَحْلِ اَلْجَاهِلِيَّةِ } أَخْرَجَهُ اِبْنُ حِبَّانَ فِي حَدِيثٍ [2]‏ صَحَّحَهُ [3]‏ .‏