Al-Kahf 18:74

<h2>The Story of killing the Boy</h2><div class="arabic uthmani">فَانطَلَقَا</div><p>(Then they both proceeded,) means, after the first incident,</p><div class="arabic uthmani">حَتَّى إِذَا لَقِيَا غُلاَمًا فَقَتَلَهُ</div><p>(till they met a boy, and he (Khidr) killed him.) It has been stated previously that this boy was playing with other boys in one of the towns, and that Al-Khidr deliberately singled him out. He was the finest and most handsome of them all, and Al-Khidr killed him. When Musa, peace be upon him, saw that he denounced him even more fervently than in the first case, and said hastily:</p><div class="arabic uthmani">أَقَتَلْتَ نَفْسًا زَكِيَّةً</div><p>(Have you killed an innocent person) meaning, a young person who had not yet committed any sin or done anything wrong, yet you killed him</p><div class="arabic uthmani">بِغَيْرِ نَفْسٍ</div><p>(without Nafs) with no reason for killing him.</p><div class="arabic uthmani">لَّقَدْ جِئْتَ شَيْئاً نُّكْراً</div><p>(Verily, you have committed a thing Nukr!) meaning, something that is clearly evil.</p><div class="arabic uthmani">قَالَ أَلَمْ أَقُلْ لَّكَ إِنَّكَ لَن تَسْتَطِيعَ مَعِىَ صَبْراً </div><p>(He said: "Did I not tell you that you can have no patience with me") Once again, Al-Khidr reiterates the condition set in the first place, so Musa says to him:</p><div class="arabic uthmani">إِن سَأَلْتُكَ عَن شَىْءٍ بَعْدَهَا</div><p>(If I ask you anything after this,) …

So they twain journeyed on till, when they met a lad, he slew him. (Moses) said: What! Hast thou slain an innocent soul who hath slain no man? Verily thou hast done a horrid thing.

Then they proceeded: until, when they met a young man, he slew him. Moses said: "Hast thou slain an innocent person who had slain none? Truly a foul (unheard of) thing hast thou done!"

Then they both proceeded, till they met a boy, he (Khidr) killed him. Musa (Moses) said: "Have you killed an innocent person who had killed none? Verily, you have committed a thing "Nukra" (a great Munkar - prohibited, evil, dreadful thing)!"

Then they set out. Until, when they encountered a boy, he killed him. He said, “Did you kill a pure soul, who killed no one? You have done something terrible.”