So they set out, until when they met a boy, al-Khidh r killed him. [Moses] said, "Have you killed a pure soul for other than [having killed] a soul? You have certainly done a deplorable thing."
The Saheeh International Quran Translation
فَٱنطَلَقَا حَتَّىٰٓ إِذَا لَقِيَا غُلَٰمًا فَقَتَلَهُۥ قَالَ أَقَتَلْتَ نَفْسًا زَكِيَّةًۢ بِغَيْرِ نَفْسٍ لَّقَدْ جِئْتَ شَيْـًٔا نُّكْرًاSo they set out, until when they met a boy, al-Khidh r killed him. [Moses] said, "Have you killed a pure soul for other than [having killed] a soul? You have certainly done a deplorable thing."