(Al-Kahf) 18 : 74
فَانْطَلَقَا حَتَّىٰ إِذَا لَقِيَا غُلَامًا فَقَتَلَهُ قَالَ أَقَتَلْتَ نَفْسًا زَكِيَّةً بِغَيْرِ نَفْسٍ لَقَدْ جِئْتَ شَيْئًا نُكْرًا
So they set out until when they met a boy; he killed him. He asked: "Have you killed a person who hadn’t killed another? Surely you have done a forbidden thing".