Word by Word Analysis

فَٱنطَلَقَا حَتَّىٰٓ إِذَا لَقِيَا غُلَـٰمًا فَقَتَلَهُۥ قَالَ أَقَتَلْتَ نَفْسًا زَكِيَّةًۢ بِغَيْرِ نَفْسٍ لَّقَدْ جِئْتَ شَيْـًٔا نُّكْرًا 74

So they set out, until when they met a boy, he [i.e., al-Khiḍr] killed him. [Moses] said, "Have you killed a pure soul for other than [having killed] a soul? You have certainly done a deplorable thing."